Abdominal adhesions are bands of tissue that form between abdominal tissues and organs. these vary from a consistency of wet tissue paper, which are of little significance, to a strong, fibrous band that can readily cause obstruction. Normally, in...

Abdominal aortic aneurysm facts An aneurysm is an abnormal area of localized widening of a blood vessel. The aorta bulges at the site of an aneurysm like a weak spot on a worn tire. Aortic aneurysms are typically ...

Abdominal aortic aneurysm facts An aneurysm is an abnormal area of localized widening of a blood vessel. The aorta bulges at the site of an aneurysm like a weak spot on a worn tire. Aortic aneurysms are typically ...

Abdominal pain facts Abdominal pain is pain that is felt in the part of the trunk below the ribs and above the pelvis. Abdominal pain comes from organs within the abdomen or organs adjacent to the abdomen. Abdomi...

Gastroschisis is a rare congenital disorder in which a defect is present in the wall of the abdomen. Typically there is a small abdominal cavity with herniated abdominal organs that usually appear on the right side of the abdomen. There is no memb...

Achalasia is a rare disease of the muscle of the esophagus (swallowing tube). The term achalasia means "failure to relax" and refers to the inability of the lower esophageal sphincter (a ring of muscle situated between the lower esophagus and the ...

Acne is a skin condition that occurs when your hair follicles become plugged with oil and dead skin cells. It often causes whiteheads, blackheads or pimples, and usually appears on the face, forehead, chest, upper back and shoulders. Acne is most ...

Understanding the key reason of adult-onset asthma and identifying unique phenotypes may hel...

Primary aldosteronism (al-DOS-tuh-ro-niz-um) is a type of hormonal disorder that leads to high blood pressure. Your adrenal glands produce a number of essential hormones. One of these is aldosterone, which balances sodium and potassium in your blo...

Reflex sympathetic dystrophy syndrome (RSDS), also known as complex regional pain syndrome, is a rare disorder of the sympathetic nervous system that is characterized by chronic, severe pain. The sympathetic nervous system is that part of the auto...

Reflex sympathetic dystrophy syndrome (RSDS), also known as complex regional pain syndrome, is a rare disorder of the sympathetic nervous system that is characterized by chronic, severe pain. The sympathetic nervous system is that part of the auto...

Allergic granulomatosis also known as Eosinophilic granulomatosis with polyangiitis (EGPA, formerly Churg-Strauss Syndro...

Allergic granulomatosis and angiitis or Eosinophilic granulomatosis with polyangiitis is a condition that affects the sm...

An aneurysm is an abnormal area of localized widening of a blood vessel. The aorta bulges at the site of an aneurysm like a weak spot on a worn tire. Aortic aneurysms are typically spindle-shaped and involve the aorta belo...

What is angina? The heart is the pump responsible for circulating blood throughout the body. Myocardium (myo=muscle + cardium=muscle) is the heart muscle that contracts to pump that blood and like any other muscle, it requires oxygen rich ...

The heart is the pump responsible for circulating blood throughout the body. Myocardium (myo=muscle + cardium=muscle) is the heart muscle that contracts to pump that blood and like any other muscle, it requires oxygen rich blood for energy. Angina...

Angular cheilitis, also known as perleche, is a common inflammatory condition that affects the corners of the mouth. It is characterized by redness, cracking, and sometimes painful sores at the corners of the lips. The condition can be caused by a...

Ankylosing spondylitis facts Ankylosing spondylitis belongs to a group of arthritis conditions that tend to cause chronic inflammation of the spine (spondyloarthropathies). Ankylosing spondylitis affects males two to three...

Torn anterior cruciate ligament (ACL) facts The anterior cruciate ligament is one of the four ligaments in the knee that provides stabilization. Torn ACLs are a common knee injury. An ACL tear or sprain occurs wh...

Introduction to aortic dissection The aorta is the large blood vessel that leads from the heart and carries blood to the rest of the body. It originates at the aortic valve at the outlet of the left ventricle of the heart and ascends withi...

What is aortic stenosis? Aortic stenosis is abnormal narrowing of the aortic valve. A number of conditions cause disease resulting in narrowing of the aortic valve. When the degree of narrowing becomes significant enough to impede the flow...

Aortic stenosis is abnormal narrowing of the aortic valve. A number of conditions cause disease resulting in narrowing of the aortic valve. When the degree of narrowing becomes significant enough to impede the flow of blood from the left ventricle...

The appendix is a small, worm-like appendage attached to the colon. Appendicitis occurs when bacteria invade and infect the wall of the appendix. The most common complications of appendicitis are rupture, abscess, and peritonitis....

Arachnoiditis is a pain disorder caused by the inflammation of the arachnoid, one of the membranes that surround and protect the nerves of the spinal cord. It is characterized by severe stinging, "burning pain", and neurological problems....

Chikungunya is a rare viral infection transmitted by the bite of an infected mosquito. It is characterized by a rash, fever, and severe joint pain (arthralgias) that usually lasts for three to seven days. Because of its effect on the joints, Chiku...

A heart arrhythmia (uh-RITH-me-uh) is an irregular heartbeat. Heart rhythm probl...

A heart arrhythmia (uh-RITH-me-uh) is an irregular heartbeat. Heart rhythm problems (heart arrhythmias) occur when the electrical signals that coordinate the heart's beats don't work properly. The faulty signalling causes the heart to beat too fas...

What is arsenic? Arsenic is a grey-appearing chemical element (atomic number 33, symbol As in the periodic table) also termed a metalloid. Arsenic can exist in a metallic state in three forms (yellow, black, and gray; with gray predominati...

Arterial chemotherapy infusion of the liver and chemoembolization of the liver (transarterial chemoembolization or TACE) are similar procedures that are used for the treatment of cancers in the liver. In both procedures, chemotherapy is injected i...

Polymyalgia rheumatica is a rare inflammatory disease characterized by muscle pain (myalgia), stiffness, and additional generalized systemic symptoms such as fatigue, low-grade fever, and/or a general feeling of ill health (malaise). Polymyalgia r...

Arthritis is the swelling and tenderness of one or more joints. The main symptoms of arthritis are joint pain and stiffness, which typically worsen with age. The most common types of arthritis are osteoarthritis and rheumatoid arthritis. O...

Arthritis is the swelling and tenderness of one or more joints. The main symptoms of arthritis are joint pain and stiffness, which typically worsen with age. The most common types of arthritis are osteoarthritis and rheumatoid arthritis. O...

Like many people with chronic ailments, sufferers of chronic arthritis are potentially vulnerable to proponents of heavily marketed "cure-all" treatments. These "quick fix" treatments are promoted as having great benefits, but in reality have no r...

Infectious arthritis is an inflammation of one or more joints that occurs as a result of infection by bacteria, viruses or, less frequently, fungi or parasites. The symptoms of Infectious arthritis depend upon which agent has caused the infection ...

Infectious arthritis is an inflammation of one or more joints that occurs as a result of infection by bacteria, viruses or, less frequently, fungi or parasites. The symptoms of Infectious arthritis depend upon which agent has caused the infection ...

Juvenile idiopathic arthritis, formerly known as juvenile rheumatoid arthritis, is the most common type of arthritis in children under the age of 16. Juvenile idiopathic arthritis can cause persistent joint pain, swelling and stiffness. So...

What is the definition of asbestos? Asbestos is a family of naturally occurring silica compounds (similar to, but not the same as, the silica of window glass and computer chips). These substances form fibers with varying shapes and sizes a...

A disorder in which a person's airways become inflamed, constrict, and bulge, as well as cre...

Atrial fibrillation (A-fib) is an irregular and often very rapid heart rhythm (a...

Atrial fibrillation (A-fib) is an irregular and often very rapid heart rhythm (arrhythmia) that can lead to blood clots in the heart. A-fib increases the risk of stroke, heart failure and other he...

Frey syndrome is a rare disorder that most often occurs as a result of surgery in the area near the parotid glands. The parotid glands are the largest salivary glands in the body located just below the ears on either side of the face. The main sym...

Jervell and Lange-Nielsen syndrome (JLNS) is a rare inherited disorder characterized by deafness present at birth (congenital) occurring in association with abnormalities affecting the electrical system of the heart. The severity of cardiac sympto...

Osteonecrosis, also known as avascular necrosis, is a disease resulting from the temporary or permanent loss of the blood supply to the bones. Without blood, the bone tissue dies and causes the bone to collapse. If the process involves the bones n...

Infectious arthritis is an inflammation of one or more joints that occurs as a result of infection by bacteria, viruses or, less frequently, fungi or parasites. The symptoms of Infectious arthritis depend upon which agent has caused the infection ...

Bacterial keratitis is an infection of the cornea, the clear outer layer of the eye, caused by bacteria. Symptoms of bacterial keratitis include redness, pain, light sensitivity, blurred vision, and discharge from the eye. Treatment typically invo...

Frey syndrome is a rare disorder that most often occurs as a result of surgery in the area near the parotid glands. The parotid glands are the largest salivary glands in the body located just below the ears on either side of the face. The main sym...

Bell's palsy (Bell palsy) is paralysis of the facial nerve of unknown cause. The diagnosis is made when no other cause can be identified. Although Bell's palsy is thought to be caused by a viral infection of the facial nerve, this hasn't been prov...

Bell's Palsy is a type of facial paralysis that results in the inability to control facial muscles on one side of the face. It is caused by damage or trauma to the facial nerve, which controls the muscles in the face. Symptoms of Bell's Palsy incl...

Bile duct cancer, also called cholangiocarcinoma, is when unusual cells grow out of control inside your bile ducts. Those are thin tubes about 4 to 5 inches long that move a fluid called bile from your liver to your gallbladder and small intestine...

Bile duct cancer, also called cholangiocarcinoma, is when unusual cells grow out of control inside your bile ducts. Those are thin tubes about 4 to 5 inches long that move a fluid called bile from your liver to your gallbladder and small intestine...

Black Eye is a mobile photography app that allows users to take and edit photos with a variety of filters, effects, and tools. It also includes features such as face recognition, portrait mode, and a variety of other editing tools....

What is the bladder? The urinary bladder, or the bladder, is a hollow organ in the pelvis. Most of it lies behind the pubic bone of the pelvis, but when full of urine, it can extend up into the lower part of the abdomen. Its primary functi...

What is the bladder? The urinary bladder, or the bladder, is a hollow organ in the pelvis. Most of it lies behind the pubic bone of the pelvis, but when full of urine, it can extend up into the lower part of the abdomen. Its primary functi...

Female urinary system Your urinary system — which includes the kidneys, ureters, bladder and urethra — is responsible for removing waste from your body through urine. Your kidneys, located toward the back in your upper abdomen,...

Female urinary system Your urinary system — which includes the kidneys, ureters, bladder and urethra — is responsible for removing waste from your body through urine. Your kidneys, located toward the back in your upper abdomen,...

Bladder infection is an infection of the bladder. Bladder infection is also called cystitis and is a type of urinary tract infection (UTI). The urinary tract is naturally sterile and when microbes invade it, an infection may result. The bl...

Bladder infection is an infection of the bladder. Bladder infection is also called cystitis and is a type of urinary tract infection (UTI). The urinary tract is naturally sterile and when microbes invade it, an infection may result. The bl...

A blocked tear duct is a condition in which the tear ducts, which normally drain tears from the eyes, become blocked or narrowed. This can cause tears to build up in the eyes, leading to watery eyes, irritation, and other symptoms. Treatment for a...

Boil  A boil is a painful, pus-filled bump under your skin — the result of a bacterial infection of one or more hair follicles. Carbuncle  A carbuncle is a cluster of boils — painful, pus-filled bumps ...

What is bone cancer? What is metastatic bone cancer? Bone cancer is a cancer of the cells that make up the bones of the body. When cancer is found in bones, it has usually started in another organ or another location in the body and has sp...

What is bone cancer? What is metastatic bone cancer? Bone cancer is a cancer of the cells that make up the bones of the body. When cancer is found in bones, it has usually started in another organ or another location in the body and has sp...

Bone spur facts A bone spur (osteophyte) is a tiny pointed outgrowth of bone. Bone spurs are usually caused by local inflammation, such as from degenerative arthritis or tendonitis. Bone spurs develop in areas of...

Parsonage-Turner syndrome is a relatively common condition characterized by inflammation of the network of nerves that control and supply (innervate) the muscles of the chest, shoulders, and arms (brachial plexus). Individuals with the condition f...

Turcot syndrome is a rare inherited disorder characterized by the association of benign growths (adenomatous polyps) in the mucous lining of the gastrointestinal tract with tumors of the central nervous system. Symptoms associated with polyp forma...

Braxton Hicks contractions are the "false" labor pains that a pregnant woman might have before “true” labor. They’re your body's way of getting ready for the real thing. But they don’t mean labor has started or is about to ...

Dengue Fever is an acute viral infection characterized by fever. It is caused by a bite from mosquitoes carrying dengue virus. The primary form of Dengue Fever is characterized by a skin rash and a high fever with severe pain in the head and muscl...

Bronchitis is an infection that causes irritation and inflammation in the lungs' major airways (bronchi). Bronchitis is divided into two types: acute and chronic. Chronic bronchitis is a long-term condition that can reoccur. Long-term stress, such...

Bronchitis is an infection that affects the lungs' major airways (bronchi), causing irritation and inflammation. Bronchitis can be classified into two types: acute and long-term. Chronic bronchitis is a long-term problem that can come back. It is usu...

Bruxism, also known as teeth grinding, is a condition characterized by the involuntary clenching, grinding, or gnashing of teeth. It can occur during the day or night, but is most commonly associated with nighttime grinding, known as sleep bruxism...

Buerger's disease (thromboangiitis obliterans) is a rare disease of the arteries and veins in the arms and legs. In Buerger's disease, your blood vessels become inflamed, swell and can become blocked with blood clots (thrombi). This eventu...

Bunions facts Bunions involve boney prominences and repositioning of the joints at the base of the big toes. Bunions most commonly affect the inner foot at the base of the big toe but also can affect the outside of the foo...

A bursa is a thin fluid-filled sac that reduces friction forces between tissues of the body. Chronic (repeated or long-standing) inflammation of the bursa (bursitis) can lead to calcification of the bursa. This is referred to as "calcific bursitis...

A bursa is a thin fluid-filled sac that reduces friction forces between tissues of the body. Chronic (repeated or long-standing) inflammation of the bursa (bursitis) can lead to calcification of the bursa. This is referred to as "calcific bursitis...

Familial articular chondrocalcinosis is a rare inherited metabolic disorder characterized by deposits of calcium pyrophosphate dihydrate crystals (CPPD) in one or more joint cartilages resulting in eventual damage to the joints. Symptoms may devel...

Camptomelic syndrome is a rare congenital disorder in which multiple anomalies are present. It is characterized by bowing and angular shape of the long bones of the legs, especially the tibia; multiple minor anomalies of the face; cleft palate; ot...

Campylobacteriosis is a bacterial infection caused by Campylobacter bacteria. It is one of the most common causes of foodborne illness in the world, typically contracted through the consumption of contaminated food or water. Symptoms of campylobac...

Camurati-Engelmann disease is a rare genetic disorder characterized by progressive widening and malformation of the shafts of the long bones (diaphyseal dysplasia). Major symptoms may include bone pain, particularly in the legs; skeletal abnormali...

Endometrial cancer Open pop-up dialog box Close Endometrial cancer Endometrial cancer Endometrial cancer begins in the lining (endometrium) of the uterus. Endometrial cancer is a type of cancer that begins in the uterus. The uterus...

Endometrial cancer begins in the lining (endometrium) of the uterus. Endometrial cancer is a type of cancer that begins in the uterus. The uterus is the hollow, pear-shaped pelvic organ where fetal development occurs. Endometrial c...

Canker sores, also known as aphthous ulcers, are small, painful sores that develop on the inside of the mouth, on the gums, or on the tongue. They are usually round or oval in shape and have a white or yellow center with a red border. Canker sores...

Carcinoid syndrome is a disease consisting of a combination of symptoms, physical manifestations, and abnormal laboratory findings. Carcinoid syndrome is seen in individuals who have an underlying carcinoid tumour with spread to the liver. Carcino...

Carcinoid syndrome is a disease consisting of a combination of symptoms, physical manifestations, and abnormal laboratory findings. Carcinoid syndrome is seen in individuals who have an underlying carcinoid tumour with spread to the liver. Carcino...

Cellulitis is a bacterial infection of the skin and underlying tissue. It is usually caused by bacteria such as Staphylococcus aureus or Streptococcus. Symptoms of cellulitis include redness, swelling, warmth, and pain in the affected area. If lef...

What is the cervix? The cervix is part of a woman's reproductive system. It's in the pelvis. The cervix is the lower, narrow part of the uterus (womb). The cervix is a passageway: The cervix connects the uterus to th...

Cheek biting, also known as cheek chewing or morsicatio buccarum, is a habit in which a person repeatedly bites or chews on the inside of their cheek. This behavior can be caused by stress, anxiety, or nervousness, and can lead to irritation, pain...

Hajdu-Cheney syndrome (HCS) is a rare, heritable disorder of connective tissue; only about 50 cases have been reported in the medical literature. The breakdown of bone (osteolysis), especially the outermost bones of the fingers and toes (acroosteo...

Chiari-Frommel Syndrome is a rare endocrine disorder that affects women who have recently given birth (postpartum) and is characterized by the over-production of breast milk (galactorrhea), lack of ovulation (anovulation), and the absence of regul...

Budd-Chiari syndrome is a rare disorder characterized by narrowing and obstruction (occlusion) of the veins of the liver (hepatic veins). Symptoms associated with Budd Chiari syndrome include pain in the upper right part of the abdomen, an abnorma...

Chickenpox (varicella) is a viral infection that causes an itchy rash with small, fluid-filled blisters. Chickenpox is highly contagious to people who haven't had the disease or been vaccinated against it. Before routine chickenpox vaccination, vi...

The virus is spread by mosquitoes and can cause severe joint pain. Chikungunya is viral infection that's spread among humans by mosquitoes that carry the virus. The infection is known for the sudden high fever and severe joint pain...

Chikungunya is a viral disease transmitted to humans by infected mosquitoes, specifically the Aedes aegypti and Aedes albopictus species. The most common symptoms of Chikungunya include fever, joint pain, headache, muscle pain, rash, and joint swe...

Chilblains (CHILL-blayns) are the painful inflammation of small blood vessels in your skin that occur in response to repeated exposure to cold but not freezing air. Also known as pernio, chilblains can cause itching, red patches, swelling and blis...

Childhood acute lymphoblastic leukemia (ALL) is a type of cancer in which the bone marrow makes too many immature lymphocytes (a type of white blood cell). Childhood acute lymphoblastic leukemia (also called acute lymphocytic leukemia or A...

Cyclic vomiting syndrome (CVS) is a rare disorder characterized by recurrent, similar episodes of severe nausea and vomiting. An episode may last for a few hours to several days and then is followed by a period of time during which affected indivi...

An epidemic is defined as occurring when "new cases of a certain disease, in a given human population during a given time period, substantially exceed what is expected based upon recent experience." Pediatric obesity has reached epidemic proportio...

A chipped tooth is a common dental injury that occurs when a portion of the tooth breaks off. This can happen due to various reasons such as biting down on a hard object, trauma to the face, or tooth decay weakening the tooth structure. A chipped ...

Chlamydia is a common sexually transmitted infection (STI) caused by the bacterium Chlamydia trachomatis. It can be transmitted through unprotected sexual contact with an infected person. Chlamydia can infect both men and women and can cause sympt...

Chlamydia is the most commonly reported sexually transmitted disease (STD) in the U.S. It is an infection with the bacteria known as Chlamydia trachomatis. Chlamydia is very similar to gonorrhea in its symptoms and pattern of transmission. It is i...

Claudication is pain and/or cramping in the lower leg due to inadequate blood flow to the muscles. The pain usually causes the person to limp. The word "claudication" comes from the Latin "claudicare" meaning to limp. Claudication typically is fel...

Cold sores, also known as fever blisters, are small blisters that typically appear on or around the lips. They are caused by the herpes simplex virus (HSV), specifically HSV-1. Cold sores are highly contagious and can be spread through close perso...

Collagenous colitis is a rare digestive disorder that primarily affects females and typically becomes apparent during middle age. The disorder is characterized by inflammatory changes of the mucous membranes (mucosa) of the colon (colitis) and abn...

Ulcerative colitis (UL-sur-uh-tiv koe-LIE-tis) is an inflammatory bowel disease ...

Ulcerative colitis (UL-sur-uh-tiv koe-LIE-tis) is an inflammatory bowel disease (IBD) that causes inflammation and ulcers (sores) in your digestive tract. Ulcerative colitis affects the innermost lining of your large intestine (colon) and rectum. ...

Colon cancer Open pop-up dialog box Close Colon cancer Colon cancer Colon cancer can occur in any part of the colon. An examination of your entire colon using a long, flexible tube equipped with a camera (colonoscopy) is one way to detect ...

Colon cancer can occur in any part of the colon. An examination of your entire colon using a long, flexible tube equipped with a camera (colonoscopy) is one way to detect colon cancer and polyps. Colon cancer is a type of cancer that begin...

Compartment syndrome describes increased pressure within a muscle compartment of the arm or leg. It is most often due to injury, such as fracture, that causes bleeding in a muscle, which then causes increased pressure in the muscle. This pressure ...

Conjunctivitis, commonly known as pink eye, is an inflammation of the conjunctiva, the thin, transparent membrane that lines the inner surface of the eyelid and covers the white part of the eye. It is usually caused by a bacterial or viral infecti...

Mixed connective tissue disease facts Connective tissues are the framework of the cells of the body. Mixed connective tissue disease is an "overlap" combination of connective tissue diseases. Diagnosis of mixed c...

Contact dermatitis facts Contact dermatitis is a rash that occurs at the site of exposure to a substance capable of producing an allegic or irritant skin response. Contact dermatitis can be caused by noxious, irritating su...

Contact lens-related eye infections are infections of the eye caused by the improper use of contact lenses. These infections can range from mild to severe and can cause a variety of symptoms, including redness, itching, burning, and blurred vision...

Corneal abrasion is a condition in which the outer layer of the cornea (the clear, dome-shaped surface that covers the front of the eye) is scratched or scraped. It is a common eye injury that can cause pain, redness, tearing, and light sensitivit...

Corneal dystrophies are a group of inherited eye disorders that cause progressive changes to the cornea, the clear outer layer of the eye. These disorders can cause vision loss and other eye problems. Symptoms vary depending on the type of corneal...

Corneal erosion is a condition in which the outer layer of the cornea (the clear, dome-shaped surface that covers the front of the eye) is damaged or worn away. This can cause pain, redness, and blurred vision. It is usually caused by trauma to th...

Corneal laceration is a tear or cut in the cornea, the clear, dome-shaped surface that covers the front of the eye. It is usually caused by a sharp object, such as a fingernail, a piece of metal, or a tree branch. Corneal lacerations can cause pai...

A corneal ulcer is an open sore on the cornea, the clear dome-shaped surface that covers the front of the eye. It is usually caused by an infection, such as bacterial, viral, or fungal, or by an injury to the eye. Symptoms of a corneal ulcer inclu...

The inflammation of the joints that connect the ribs to the breast bone is known as costochondritis. Costochondritis can develop as a result of genetics, viruses, or even an accident. Costochondritis can be a separate medical condition or a sympto...

Carnitine palmitoyltransferase 1A deficiency (CPT1A) is characterized by a sudden onset of liver failure and damage to the nervous system resulting from liver failure (hepatic encephalopathy), usually associated with fasting or illness. CPT1A defi...

A cracked tooth is a common dental problem that occurs when a tooth has a visible crack or fracture in the enamel. This can happen due to a variety of reasons, such as biting down on a hard object, grinding teeth, or trauma to the mouth. Cracked t...

Adenoid cystic carcinoma (ACC) is a relatively rare form of cancer that most commonly develops in the salivary glands or other regions of the head and neck. In some cases, ACC may arise in other primary sites, such as the skin; the breast; the nec...

Crohn's disease facts Crohn's disease is a chronic inflammatory disease of the intestines. The cause of Crohn's disease is unknown. Crohn's disease can cause ulcers in the small intestine, colon, or both. ...

Crossbite is a dental condition in which the upper teeth do not align properly with the lower teeth when the jaw is closed. This misalignment can occur on one side of the mouth (unilateral crossbite) or on both sides (bilateral crossbite). Crossbi...

Crowded teeth, also known as dental crowding, is a common orthodontic issue where there is not enough space in the mouth for all of the teeth to align properly. This can result in teeth overlapping, twisting, or becoming crooked. Crowded teeth can...

Mixed cryoglobulinemia is a rare disorder characterized by the presence of cryoglobulins in the blood. Cryoglobulins are abnormal proteins that thicken and clump together at cold temperatures, usually below 98.6 degrees Fahrenheit (the average hum...

Cryptococcus is a fungus that is found in soil all over the world, usually in association with bird droppings. Cryptococcus neoformans is the most common Cryptococcus species that causes illness in humans. Cryptococcus gattii, a less common specie...

An interstitial lung disease occurs when there is cryptogenic fibrous alveolitis in the lungs (or ILD for short). They have an impact on the tissues that support the air sacs in the lungs, making it difficult for them to take in as much air as the...

Cryptosporidiosis is a diarrheal disease caused by microscopic parasites, Cryptosporidium, that can live in the intestine of humans and animals and is passed in the stool of an infected person or animal. Both the disease and the parasite are commo...

Cyclic vomiting syndrome is characterized by episodes of severe vomiting that ha...

Autosomal dominant interstitial kidney disease describes a group of diseases affecting solely the proper function of the kidney and having the following characteristics: They are inherited in an autosomal dominant manner; kidney disease develops, ...

Autosomal dominant interstitial kidney disease describes a group of diseases affecting solely the proper function of the kidney and having the following characteristics: They are inherited in an autosomal dominant manner; kidney disease develops, ...

Cystinuria facts Cystinuria is a relatively common inherited disorder. The disorder is due to a defect in the transport of amino acids including one called cystine. Cystinuria features too much cystine in the uri...

Autosomal dominant interstitial kidney disease describes a group of diseases affecting solely the proper function of the kidney and having the following characteristics: They are inherited in an autosomal dominant manner; kidney disease develops, ...

Cytomegalovirus infection (CMV) is a viral infection that rarely causes obvious illness. The virus that causes CMV is part of the herpes virus family and, like other herpes viruses, may become dormant for a period of time and then be reactivated. ...

General DiscussionThe word "neurasthenia" is a term that has fallen into disuse among psychiatrists in the United States and Australia. It remains in use in the United Kingdom. Where it is used, it covers a wide spectrum of symptoms inclu...

De Quervain's tenosynovitis is inflammation of tendons on the side of the wrist at the base of the thumb. These tendons include the extensor pollicis brevis and the abductor pollicis longus tendons, which extend the joints of the thumb. De...

General DiscussionJervell and Lange-Nielsen syndrome (JLNS) is a rare inherited disorder characterized by deafness present at birth (congenital) occurring in association with abnormalities affecting the electrical system of the heart. The...

Degenerative disc disease and sciatica facts The discs of the spine serve as "cushions" between each vertebral segment. The discs are designed somewhat like a jelly donut. Degeneration (deterioration) of the disc...

Degos disease is an extremely rare disorder in which small and medium sized arteries become blocked (occlusive arteriopathy), restricting the flow of blood to affected areas. Degos disease usually causes characteristic skin lesions that may last f...

Degos disease is an extremely rare disorder in which small and medium sized arteries become blocked (occlusive arteriopathy), restricting the flow of blood to affected areas. Degos disease usually causes characteristic skin lesions that may last f...

Dejerine-Sottas disease is an inherited neurological disorder that progressively affects mobility. Peripheral nerves become enlarged or thickened leading to muscle weakness. Progress of the disorder is irregular and often accompanied by pain, weak...

Central pain syndrome is a neurological disorder caused by damage to the central nervous system (CNS). Common symptoms include pain and loss of sensation, usually in the face, arms and/or legs. Pain is often constant and can be mild, moderate, or ...

Dental cavitation, also known as a cavitation lesion or a cavitation, is a hole or hollow space in the jawbone that is caused by a chronic infection or inflammation in the bone. These cavitations can occur after a tooth extraction, root canal trea...

Dental hypersensitivity, also known as tooth sensitivity, is a common dental problem characterized by a sharp pain or discomfort in the teeth when exposed to certain stimuli such as hot or cold temperatures, sweet or acidic foods, or even brushing...

Dental trauma refers to any injury or damage to the teeth, gums, or surrounding tissues caused by a sudden force or impact. This can include fractures, chips, dislodged teeth, or injuries to the soft tissues of the mouth. Dental trauma can result ...

A dentigerous cyst is a type of odontogenic cyst that forms around the crown of an unerupted or developing tooth. It is the second most common type of odontogenic cyst and is typically associated with impacted teeth, most commonly the third molars...

Diabetes and foot problems facts Two main conditions, peripheral artery disease (PAD) and peripheral neuropathy, are responsible for the increased risk of foot problems in people with diabetes. People with diabetes have an...

Diabetic ketoacidosis is a serious complication of diabetes that occurs when you...

Diabetic ketoacidosis is a serious complication of diabetes that occurs when you...

Neuropathy is damage to nerves, and diabetic neuropathy is damage to nerves that occurs as a result of diabetes. Diabetes is thought to damage nerves as a result of prolonged elevated levels of blood glucose. Diabetic neuropathy can affect differe...

Hereditary multiple osteochondromas (HMO) is a rare genetic disorder characterized by multiple benign (noncancerous) bone tumors that are covered by cartilage (osteochondromas), often on the growing end (metaphysis) of the long bones of the legs, ...

Camurati-Engelmann disease is a rare genetic disorder characterized by progressive widening and malformation of the shafts of the long bones (diaphyseal dysplasia). Major symptoms may include bone pain, particularly in the legs; skeletal abnormali...

Dislocated ankle facts An isolated dislocated ankle is a rare injury. Usually, there is an associated fracture of the bones that make up the ankle. The ankle dislocates as a result of a fall, motor-vehicle crash, or sporti...

Diverticulosis and diverticulitis facts Most patients with diverticulosis (diverticular disease) have few or no symptoms. Abdominal pain, constipation, and diarrhea, can occur with diverticulosis, which then may be called ...

Dry socket, also known as alveolar osteitis, is a painful dental condition that can occur after a tooth extraction. It occurs when the blood clot that forms in the socket where the tooth was removed becomes dislodged or dissolves before the wound ...

Though ulcers often heal on their own, you shouldn't ignore their warning signs. If not properly treated, ulcers can lead to serious health problems, including: Bleeding Perforation (a hole through the wall of the stomach)...

Dupuytren's contracture facts A Dupuytren's contracture is a localized scar tissue formation in the palm. The precise cause of a Dupuytren's contracture is not known. A Dupuytren's contracture is sometimes inheri...

Familial dysautonomia is a rare genetic disorder of the autonomic nervous system (ANS) that primarily affects people of Eastern European Jewish heritage. It is characterized by diminished sensitivity to pain, lack of overflow tearing in the eyes, ...

Dysplasia epiphysealis hemimelica, also known as Trevor disease, is a rare skeletal developmental disorder of childhood. It is characterized by an overgrowth of cartilage on the ends (epiphyses) of the long bones of the arms and legs and the bones...

Ehlers-Danlos syndrome (EDS) is a group of hereditary connective tissue disorders characterized by defects of the major structural protein in the body (collagen). Collagen, a tough, fibrous protein, plays an essential role in holding together, str...

Escherichia coli (E. coli) bacteria normally live in the intestines of healthy people and animals. Most varieties of E. coli are harmless or cause relatively brief diarrhea. But a few particularly nasty strains, such as E. coli O157:H7, can cause ...

E. coli infection is a type of bacterial infection caused by the bacterium Escherichia coli. E. coli bacteria are commonly found in the intestines of humans and animals, and most strains are harmless. However, some strains of E. coli can cause ill...

An ectopic pregnancy is a pregnancy located outside the inner lining of the uterus. Risk factors for ectopic pregnancy include previous ectopic pregnancies and conditions (surgery, infection) that disrupt the normal anatomy of the F...

Ehlers-Danlos syndrome (EDS) is a group of hereditary connective tissue disorders characterized by defects of the major structural protein in the body (collagen). Collagen, a tough, fibrous protein, plays an essential role in holding together, str...

Elbow pain facts The elbow joint is the area of union of three long bones. Tendinitis can affect the inner or outer elbow. Treatment of tendinitis includes ice, rest, and medication for inflammation. Ba...

Williams syndrome, also known as Williams-Beuren syndrome, is a rare genetic disorder characterized by growth delays before and after birth (prenatal and postnatal growth retardation), short stature, a varying degree of mental deficiency, and dist...

Atrioventricular septal defect (ASVD) is a general term for a group of rare heart defects that are present at birth (congenital). Infants with ASVDs have improperly developed atrial and ventricular septa and adjoining valves. The norma...

Endocardial fibroelastosis (EFE) is a rare heart disorder that affects infants and children. It is characterized by a thickening within the muscular lining of the heart chambers due to an increase in the amount of supporting connective tissue (ine...

Endometrial ablation facts Endometrial ablation is the surgical destruction of the lining tissues of the uterus. Endometrial ablation is one type of treatment for abnormal uterine bleeding that is due to a benign (non-canc...

Endometriosis is the abnormal growth of cells (endometrial cells) similar to those that form the inside of the uterus, but in a location outside of the uterus. Endometriosis is most commonly found on other organs of the pelvis. The ...

Endophthalmitis is an inflammation of the inner layers of the eye, usually caused by an infection. It can be caused by bacteria, fungi, or viruses, and can lead to vision loss if not treated promptly. Symptoms of endophthalmitis include redness, p...

Tuberous sclerosis is a rare genetic multisystem disorder that is typically apparent shortly after birth. The disorder may be characterized by episodes of uncontrolled electrical activity in the brain (seizures); mental retardation; distinctive sk...

An eruption cyst is a benign, soft tissue swelling that occurs in the mouth when a tooth is about to erupt through the gum. It appears as a small, fluid-filled blister that is usually purple or blue in color. Eruption cysts are most commonly seen ...

Erythema multiforme (EM) is the name applied to a group of hypersensitivity disorders, affecting mostly children and young adults, and characterized by symmetric red, patchy lesions, primarily on the arms and legs. The cause is unknown, but EM fre...

Until recently the relationship of Stevens-Johnson syndrome to other severe blistering disorders was a matter of some debate. Now a consensus seems to be evolving that describes SJS as a rare disorder involving lesions of the mucous membranes alon...

Erythema nodosum is a type of skin inflammation that is located in a certain portion of the fatty layer of skin. Erythema nodosum (also called EN) results in reddish, painful, tender lumps most commonly located in the front of the legs below the k...

Erythromelalgia is a rare condition that primarily affects the feet and, less commonly, the hands (extremities). It is characterized by intense, burning pain of affected extremities, severe redness (erythema), and increased skin temperature that m...

Erythropoietic protoporphyria (EPP) is a rare inherited metabolic disorder characterized by a deficiency of the enzyme ferrochelatase (FECH). Due to abnormally low levels of this enzyme, excessive amounts of protoporphyrin accumulate in the bone m...

Achalasia is a rare disorder of the esophagus, the tube that carries food from the throat to the stomach. It is characterized by enlargement of the esophagus, impaired ability to push food down toward the stomach (peristalsis), and failure of the ...

What is the esophagus? The esophagus is a muscular tube in the chest. It's about 10 inches (25 centimeters) long. This organ is part of the digestive tract. Food moves from the mouth through the esophagus to the stomach. Th...

Cryoglobulinemia is a medical condition that is caused by proteins called cryoglobulins, which are present in the blood. Cryoglobulins are abnormal proteins that by definition have the unusual property of precipitating from the serum when it is ch...

Cryptococcosis is caused by a fungus known as Cryptococcosis neoformans. The infection may be spread to humans through contact with pigeon droppings or unwashed raw fruit. Contact with an infected individual may also spread the infection. Individu...

General DiscussionCongenital rubella is a syndrome that occurs when a fetus has been infected with the rubella virus while in the uterus. It is primarily characterized by abnormalities of the heart and nervous system, the eyes and the ear...

Fabry disease is caused by the lack of or faulty enzyme needed to metabolize lipids, fat-like substances that include oils, waxes, and fatty acids. The enzyme is known as ceramide trihexosidase, also called alpha-galactosidase-A. A mutation in the...

Pediatric cardiomyopathy is a rare heart condition that affects infants and children. Specifically, cardiomyopathy means disease of the heart muscle (myocardium). Several different types of cardiomyopathy exist and the specific symptoms vary from ...

Peeling skin syndrome is a rare inherited skin disorder characterized by painless, continual, spontaneous skin peeling (exfoliation). Other findings may include blistering and/or reddening of the skin (erythema) and itching (pruritus). Peeling ski...

Familial eosinophilic cellulitis is a rare skin disorder. It is characterized by raised, red, swollen, and warm areas of skin, in a flame-shaped pattern with associated pain. The exact cause of the disease is unknown. However, bites of spiders, be...

Familial lipoprotein lipase (LPL) deficiency is a rare genetic metabolic disorder characterized by a deficiency of the enzyme lipoprotein lipase. The deficiency of this enzyme prevents affected individuals from properly digesting certain fats and ...

Fibrocystic breast changes  Fibrocystic breast changes lead to the development of fluid-filled round or oval sacs (cysts) and more prominent scar-like (fibrous) tissue, which can make breasts feel tender, lumpy or ropy. Fibroc...

A fibroma is a benign tumor that is composed of fibrous or connective tissue. It can develop in various parts of the body, including the skin, organs, and soft tissues. Fibromas are typically slow-growing and non-cancerous, but they can cause symp...

Fibromyalgia facts Fibromyalgia is a pain syndrome characterized by chronic pain, fatigue, and tenderness to touch. Fibromyalgia is the most common cause of chronic, widespread pain in the United States. Fibromya...

Fibrosing Alveolitis, also known as Pulmonary Fibrosis, is a lung condition that affects the tissues that support the air sacs. As a result, it is more difficult for them to absorb the necessary oxygen for respiration. The lung tissues thicken and...

General DiscussionWeil syndrome, a rare infectious disorder, is a severe form of the bacterial infection caused by Leptospira bacteria known as leptospirosis. Weil syndrome is characterized by dysfunction of the kidneys and liver, abnorma...

Fitz-Hugh-Curtis syndrome is a rare disorder that occurs almost exclusively in women. It is characterized by inflammation of the membrane lining the stomach (peritoneum) and the tissues surrounding the liver (perihepatitis). The muscle that separa...

You have flatfeet when the arches on the inside of your feet are flattened, allowing the entire soles of your feet to touch the floor when you stand up. A common and usually painless condition, flatfeet can occur when the arches don't deve...

Your feet bear weight when you’re standing and when you walk to where you need to go. Because of this, foot pain is common. Foot pain refers to any pain or discomfort in one or more parts of the foot, such as the following: to...

Trigeminal neuralgia, also known as tic douloureux, is a disorder of the fifth cranial nerve (trigeminal nerve) characterized by attacks of intense, stabbing pain affecting the mouth, cheek, nose, and/or other areas on one side of the face. The ex...

Frozen shoulder facts Frozen shoulder is the result of scarring, thickening, and shrinkage of the joint capsule. Any injury to the shoulder can lead to a frozen shoulder. A frozen shoulder is usually diagnosed du...

Frozen shoulder Frozen shoulder occurs when the connective tissue enclosing the joint becomes thickened and tight. Frozen shoulder, also known as adhesive capsulitis, is a condition characterized by stiffness and pain in your shoul...

Fuchs' Dystrophy is a type of corneal dystrophy, a disorder that affects the cornea, the clear outer layer of the eye. It is a slowly progressive disorder that usually affects both eyes. Symptoms include blurred vision, sensitivity to light, and d...

The word "neurasthenia" is a term that has fallen into disuse among psychiatrists in the United States and Australia. It remains in use in the United Kingdom. Where it is used, it covers a wide spectrum of symptoms including the sensation of pain ...

Fungal keratitis is an infection of the cornea, the clear outer layer of the eye, caused by a fungus. It is a rare but serious condition that can cause vision loss if not treated promptly. Symptoms of fungal keratitis include redness, pain, blurre...

Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency (G6PDD) is an inherited, sex-linked, metabolic disorder characterized by an enzyme defect that leads to the breakdown of red blood cells (hemolysis) upon exposure to stresses associated with some...

Schindler disease is a rare inherited metabolic disorder characterized by the deficient activity of the lysosomal enzyme alpha-N-acetylgalactosaminidase (alpha-NAGA or alpha-galactosidase B). The enzyme defect leads to the abnormal accumulation of...

Gangrene facts Gangrene refers to dead or dying body tissue(s) that occur because of inadequate blood supply. There are two major types of gangrene, wet gangrene and dry gangrene. Dry gangrene can result from con...

Gastritis is inflammation of the lining of the stomach. Unfortunately, the term "gastritis" has been misused to include many different upper abdominal problems, but true gastritis refers to the stomach lining (gastric mucosa) that is inflamed. All...

Definition of gastroenteritis Gastroenteritis (often referred to as the "stomach flu," however, it is not related to the influenza virus. Gastroenteritis is a nonspecific term for various inflammatory problems in the gastrointestinal tract...

Genital herpes, also known as herpes simplex virus type 2 (HSV-2), is a sexually transmitted infection that causes painful sores and blisters on the genital area. It is a chronic condition that can flare up periodically, causing symptoms such as i...

Genital warts are a sexually transmitted infection caused by the human papillomavirus (HPV). They are small, flesh-colored bumps or growths that appear on or around the genital area. Genital warts can be spread through sexual contact and are highl...

Giant cell myocarditis is a rare cardiovascular disorder that occurs for unknown reasons (idiopathic). It is characterized by inflammation of the heart muscle (myocardium), a condition referred to as myocarditis. Inflammation is caused by widespre...

Giant Papillary Conjunctivitis (GPC) is an inflammatory condition of the eye that affects the inner surface of the eyelids. It is caused by an allergic reaction to contact lenses, foreign bodies, or other irritants. Symptoms include itching, redne...

Giardiasis is a common intestinal infection caused by a microscopic parasite called Giardia lamblia. It is typically contracted by ingesting contaminated food or water, and can cause symptoms such as diarrhea, abdominal cramps, bloating, and weigh...

Progeria, or Hutchinson-Gilford progeria syndrome (HGPS), is a rare, fatal, genetic condition of childhood with striking features resembling premature aging. Children with progeria usually have a normal appearance in early infancy. At approximatel...

Glaucoma is a disease that is often associated with elevated intraocular pressure, in which damage to the eye (optic) nerve can lead to loss of vision and even blindness. Glaucoma is the leading cause of irreversible blindness in th...

Glaucoma is a group of eye diseases that damage the optic nerve, which carries information from the eye to the brain. It is usually caused by an abnormally high pressure in the eye, which can damage the optic nerve and lead to vision loss. Glaucom...

Turcot syndrome is a rare inherited disorder characterized by the association of benign growths (adenomatous polyps) in the mucous lining of the gastrointestinal tract with tumors of the central nervous system. Symptoms associated with polyp forma...

Glossitis is a condition characterized by inflammation of the tongue. This inflammation can cause the tongue to become swollen, red, and painful. Glossitis can be caused by a variety of factors, including infections, allergies, nutritional deficie...

Glucose-galactose malabsorption is an inherited metabolic disorder characterized by the small intestine's inability to transport and absorb glucose and galactose (simple sugars or monosaccharides). Glucose and galactose have very similar chemical ...

Forbes disease (GSD-III) is one of several glycogen storage disorders (GSD) that are inherited as autosomal recessive traits. Symptoms are caused by a lack of the enzyme amylo-1,6 glucosidase (debrancher enzyme). This enzyme deficiency causes exce...

Fabry disease is a rare genetic disorder of fat (lipid) metabolism characterized by a deficiency of the enzyme alpha-galactosidase A (previously known as ceramide trihexosidase). The disorder belongs to a group of diseases known as lysosomal stora...

Gonorrhea is a sexually transmitted infection (STI) caused by the bacterium Neisseria gonorrhoeae. It can infect both men and women and is most commonly spread through unprotected sexual contact. Symptoms of gonorrhea can include painful urination...

Gonorrhea is a bacterial infection that is transmitted during sexual activity. Gonorrhea is not transmitted from toilet seats. Women infected with gonorrhea may not have any symptoms. Gonorrhea is treated with an...

Gout is a type of arthritis that causes inflammation, usually in one joint, that begins suddenly. Gouty arthritis is caused by the deposition of crystals of uric acid in a joint. Gout can cause symptoms and signs such as ...

Gout is a type of arthritis that causes inflammation, usually in one joint, that begins suddenly. Gouty arthritis is caused by the deposition of crystals of uric acid in a joint. Gout can cause symptoms and signs such as ...

Acquired agranulocytosis is a rare, drug-induced blood disorder that is characterized by a severe reduction in the number of white blood cells (granulocytes) in the circulating blood. The name granulocyte refers to grain-like bodies within the cel...

SHORT syndrome is a condition in which affected individuals have multiple birth defects in different organ systems. The term SHORT is an acronym with each letter representing one of the common findings in affected persons:(S)= short st...

Lichen sclerosus is a chronic skin disorder that most commonly affects post-menopausal women. However, it is sometimes identified among pre-menopausal women, and, even more rarely, among males. When found in males, the disease is known as balaniti...

A heart attack occurs when the flow of blood to the heart is severely reduced or...

Cardiac catheterization (also called cardiac cath or coronary angiogram) is an invasive imaging procedure that tests for heart disease by allowing your doctor to see how well your heart is functioning. During the test, a long, narrow tube, called ...

Cardiac catheterization (also called cardiac cath or coronary angiogram) is an invasive imaging procedure that tests for heart disease by allowing your doctor to see how well your heart is functioning. During the test, a long, narrow tube, called ...

Heart disease is the leading cause of death among women. An estimated 90% of women have at least one risk factor for heart disease. Heart attack symptoms can be different for women than for men. Younger women wit...

Heart disease is the leading cause of death among women. An estimated 90% of women have at least one risk factor for heart disease. Heart attack symptoms can be different for women than for men. Younger women wit...

According to the American Heart Association, about 5 million Americans are diagnosed with valvular heart disease each year. What Is Valvular Heart Disease? Heart valve disease occurs when your heart's valves do not work the way the...

Introduction to heart transplant The idea of replacing a bad organ with a good one has been documented in ancient mythology. The first real organ transplants were probably skin grafts that may have been done in India as early as the second...

Helicobacter pylori (H. pylori) facts Helicobacter pylori (H. pylori) is a bacterium that causes chronic inflammation in the stomach and is a common cause of ulcers worldwide H. pylori causes chronic inflammation (gastriti...

Hemangioma is a noncancerous growth of blood vessels that can occur anywhere in the body. It is most commonly found on the skin or internal organs, such as the liver or lungs. Hemangiomas are usually present at birth or develop shortly after and c...

A hematoma is a collection of blood outside of a blood vessel. Symptoms of hematomas depend upon their location and whether adjacent structures are affected by the inflammation and swelling associated with the bleeding. Tr...

Hemolytic uremic syndrome (HUS) is a condition caused by the abnormal destruction of red blood cells. The damaged red blood cells clog the filtering system in the kidneys, which can lead to life-threatening kidney failure. HUS usually deve...

Hepatitis A is a highly contagious liver infection caused by the hepatitis A virus. It is typically spread through contaminated food or water, or through close contact with an infected person. Symptoms of hepatitis A can include fever, fatigue, lo...

Hepatitis B is a viral infection that attacks the liver and can cause both acute and chronic disease. The virus is transmitted through contact with the blood or other body fluids of an infected person. Hepatitis B can be a mild illness lasting a f...

Hepatitis C is a viral infection that causes liver inflammation, sometimes leading to serious liver damage. The hepatitis C virus (HCV) is spread through contact with infected blood, most commonly through sharing needles or other equipment used to...

Hepatitis D, also known as delta hepatitis, is a liver infection caused by the hepatitis D virus (HDV). HDV is a small, defective RNA virus that can only replicate in the presence of the hepatitis B virus (HBV). This means that a person can only g...

Hepatitis E is a liver infection caused by the hepatitis E virus (HEV). It is typically a self-limiting illness that resolves on its own within a few weeks. However, in some cases, it can cause acute liver failure, especially in pregnant women and...

Hepatorenal syndrome (HRS) is a form of impaired kidney function that occurs in individuals with advanced liver disease. Individuals with hepatorenal syndrome do not have any identifiable cause of kidney dysfunction and the kidneys themselves are ...

Familial dysautonomia is a rare genetic disorder of the autonomic nervous system (ANS) that primarily affects people of Eastern European Jewish heritage. It is characterized by diminished sensitivity to pain, lack of overflow tearing in the eyes, ...

Hereditary spherocytic hemolytic anemia is a rare blood disorder characterized by defects within red blood cells (intracorpuscular) that result in a shortened survival time for these cells. Red blood cells (erythrocytes) normally circulate for a f...

Herniated disc facts The discs are pads that serve as "cushions" between the vertebral bodies, which minimize the impact of movement on the spinal column. Each disc is designed like a jelly donut with a central softer comp...

Herpes Keratitis is an infection of the cornea caused by the herpes simplex virus (HSV). It is a common cause of corneal blindness and can cause severe vision loss if left untreated. Symptoms of Herpes Keratitis include redness, pain, light sensit...

Herpes Simplex Virus (HSV) is a common viral infection that causes sores or blisters on the skin or mucous membranes. There are two types of HSV: HSV-1, which typically causes cold sores or fever blisters around the mouth, and HSV-2, which typical...

Herpetic gingivostomatitis is a viral infection caused by the herpes simplex virus. It is characterized by painful sores and ulcers in the mouth and on the gums, as well as fever, swollen lymph nodes, and general malaise. It is a common infection ...

Hidradenitis suppurativa (HS) is a chronic condition characterized by swollen, painful lesions, occurring in the armpit (axillae), groin, anal, and breast regions. This disease occurs due to obstruction of hair follicles and secondary infection an...

Hidradenitis suppurativa (hi-drad-uh-NIE-tis sup-yoo-ruh-TIE-vuh) is rare, long-term skin condition that features small, painful lumps under the skin. They typically develop where the skin rubs together, such as the armpits, the groin, between the...

Hidradenitis suppurativa (HS) is a chronic condition characterized by swollen, painful lesions, occurring in the armpit (axillae), groin, anal, and breast regions. This disease occurs due to obstruction of hair follicles and secondary infection an...

Kikuchi's disease, also known as histiocytic necrotizing lymphadenopathy, is a rare, benign, (noncancerous, nonmalignant) disorder of the lymph nodes of young adults, predominantly in young women. This disorder is often mistaken for malignant lymp...

Langerhans cell histiocytosis (LCH) is a spectrum of rare disorders characterized by overproduction (proliferation) and accumulation of a specific type of white blood cell (histiocyte) in the various tissues and organs of the body (lesions). The l...

Histoplasmosis is an infection caused by the fungus Histoplasma. The fungus can be found in the environment, particularly in soil with a high concentration of bird or bat droppings. Histoplasma is mostly found in the central and eastern United Sta...

Papular urticaria, usually called hives, is characterized by large numbers of very itchy red bumps (papules) that come and go every few days over a period of a month or so. The bumps are usually between 0.2 and 2 cm. in size and some may develop i...

Hydrocele facts While hydroceles may occur in either gender, they are much more common in males. A hydrocele is a collection of clear fluid in a thin walled sack present in the scrotum. Hydroceles may be either o...

Bartter's syndrome (BS) is a group of conditions involving enlargement of certain kidney cells, blood that is more alkaline than normal, high levels of potassium and chloride in the urine, loss of potassium from the kidneys (renal potassium wastin...

Williams syndrome, also known as Williams-Beuren syndrome, is a rare genetic disorder characterized by growth delays before and after birth (prenatal and postnatal growth retardation), short stature, a varying degree of mental deficiency, and dist...

Familial lipoprotein lipase (LPL) deficiency is a rare genetic metabolic disorder characterized by a deficiency of the enzyme lipoprotein lipase. Deficiency of this enzyme prevents affected individuals from properly digesting certain fats and resu...

Hyperdontia, also known as supernumerary teeth, is a condition in which a person has extra teeth in addition to the normal set of primary or permanent teeth. These extra teeth can develop in any area of the mouth and may be single or multiple in n...

High blood sugar (hyperglycemia) affects people who have diabetes. Several facto...

Hypermobility syndrome facts The joint hypermobility syndrome is a condition that features joints that easily move beyond the normal range expected for a particular joint. Hypermobile joints tend to be inherited. ...

Hyphema is a condition in which there is bleeding in the front chamber of the eye, between the cornea and the iris. It is usually caused by trauma to the eye, such as a blunt force or a sharp object. Symptoms of hyphema include blurred vision, red...

Thyroid disease is particularly common in women of child-bearing age. As a result, it is no surprise that thyroid disease may complicate the course of pregnancy. Frequency varies among different populations and different c...

IBS triggers and prevention facts Foods and drinks that dehydrate the body can trigger constipation in IBS patients. Fatty foods can trigger diarrhea in people with IBS; others may also do so but specific food triggers of di...

General DiscussionPediatric cardiomyopathy is a rare heart condition that affects infants and children. Specifically, cardiomyopathy means disease of the heart muscle (myocardium). Several different types of cardiomyopathy exist and the s...

General DiscussionGiant cell myocarditis is a rare cardiovascular disorder that occurs for unknown reasons (idiopathic). It is characterized by inflammation of the heart muscle (myocardium), a condition referred to as myocarditis. Inflamm...

IgA nephropathy (nuh-FROP-uh-thee), also known as Berger's disease, is a kidney disease that occurs when an antibody called immunoglobulin A (IgA) lodges in your kidneys. This results in local inflammation that, over time, may hamper your kidneys'...

If you’ve got a nagging pain on the outer part of your knee, especially if you’re a runner, it could be a symptom of iliotibial band (IT band) syndrome. It’s an injury often caused by activities where you bend your knee repeatedl...

Impacted wisdom teeth are third molars at the back of the mouth that do not have enough room to emerge or develop normally. This can cause them to become trapped or impacted in the jawbone or gum tissue, leading to pain, swelling, infection, and o...

Dyspepsia (indigestion) facts Dyspepsia is a functional disease in which the gastrointestinal organs, primarily the stomach and first part of the small intestine, function abnormally. It is a chronic disease in which the symptoms fl...

Interstitial cystitis facts PBS/IC is an inflammatory disease of the bladder that can cause ulceration and bleeding of the bladder's lining and can lead to scarring and stiffening of the bladder. The symptoms of PBS/IC are...

Intertrigo is a dermatitis that only affects skin folds. Intertrigo is caused when skin is irritated by friction, which is enhanced by moisture and heat. Risk factors for intertrigo include obesity, heat, and humidity....

Intussusception facts Intussusception is the infolding (telescoping) of one segment of the intestine within another. Intussusception usually results in a blockage of the intestine. Intussusception occurs primaril...

Iridocorneal Endothelial Syndrome (ICE Syndrome) is a rare eye disorder that affects the cornea, iris, and endothelium. It is characterized by corneal edema, iris atrophy, and endothelial cell loss. Symptoms may include blurred vision, glare, halo...

What is the definition of irritable bowel syndrome (IBS)? Irritable bowel syndrome (IBS) is a gastrointestinal disorder characterized by the presence of a cluster of symptoms and signs in adult or children that include cramping, abdominal ...

What is irritable bowel syndrome (IBS)? Irritable bowel syndrome is a functional gastrointestinal (GI) disorder, meaning it is a problem caused by changes in how the GI tract works. Children with a functional GI disorder have frequent symp...

Osteonecrosis, also known as avascular necrosis, is a disease resulting from the temporary or permanent loss of the blood supply to the bones. Without blood, the bone tissue dies and causes the bone to collapse. If the process involves the bones n...

Jansen type metaphyseal chondrodysplasia is an extremely rare progressive disorder in which portions of the bones of the arms and legs develop abnormally with unusual cartilage formations and subsequent abnormal bone formation at the large (bulbou...

Jaw clicking is a common symptom of temporomandibular joint (TMJ) disorder, which is a condition that affects the jaw joint and surrounding muscles. When a person with TMJ disorder opens or closes their mouth, the jaw joint may make a clicking or ...

Jaw dislocation occurs when the lower part of the jawbone (mandible) is moved out of its normal position at one or both of the temporomandibular joints (TMJ). This can happen as a result of trauma, such as a blow to the face, or due to excessive j...

Until recently the relationship of Stevens-Johnson syndrome to other severe blistering disorders was a matter of some debate. Now a consensus seems to be evolving that describes SJS as a rare disorder involving lesions of the mucous membranes alon...

Juvenile Idiopathic Arthritis Uveitis (JIAU) is a type of eye inflammation that is associated with juvenile idiopathic arthritis (JIA). It is a rare condition that affects the uvea, which is the middle layer of the eye. Symptoms of JIAU include re...

Dercum's disease is an extremely rare disorder characterized by multiple, painful growths consisting of fatty tissue (lipomas). These growths mainly occur on the trunk, the upper arms and upper legs and are found just below the skin (subcutaneousl...

Kawasaki's disease facts Kawasaki's disease is a syndrome of unknown cause that mainly strikes young children. Signs of the disease include fever and redness of the eyes, hands, feet, mouth, and tongue. The disea...

Kienbock Disease is an acquired bone disorder. Abnormalities of the lunate bone in the wrist develops following an injury or inflammation. Recurrent pain and stiffness occur in conjunction with thickening, swelling and tenderness in soft tissue ov...

Kikuchi's disease, also known as histiocytic necrotizing lymphadenopathy, is a rare, benign, (noncancerous, nonmalignant) disorder of the lymph nodes of young adults, predominantly in young women. This disorder is often mistaken for malignant lymp...

Knee bursitis facts A bursa is a fluid-filled sac that functions as a gliding surface to reduce friction between moving tissues of the body. There are three major bursae of the knee. Bursitis is usually not infec...

Knee injury facts The knee is one of the most common body parts to be injured. Types of knee injuries include sprains, strains, bursitis, dislocations, fractures, meniscus tears, and overuse injuries. Knee injuri...

Knee pain facts Knee pain is a common problem with many causes, from acute injuries to medical conditions. Knee pain can be localized or diffuse throughout the knee. Knee pain is often accompanied by physical res...

Kniest dysplasia is one of several forms of dwarfism that is caused by a change (mutation) in a gene known as COL2A1. This gene is involved in the production of a particular protein that forms type 2 collagen, which is essential for the normal dev...

Kniest dysplasia is one of several forms of dwarfism that is caused by a change (mutation) in a gene known as COL2A1. This gene is involved in the production of a particular protein that forms type 2 collagen, which is essential for the normal dev...

A knocked-out tooth, also known as an avulsed tooth, is a tooth that has been completely displaced from its socket in the jawbone due to trauma or injury. This can happen as a result of a sports injury, car accident, or a fall. It is important to ...

Kohler disease is a rare bone disorder of the foot in children that may be the result of stress-related compression at a critical time during the period of growth. It is characterized by limping caused by pain and swelling in the foot. It most oft...

Kohler disease is a rare bone disorder of the foot in children that may be the result of stress-related compression at a critical time during the period of growth. It is characterized by limping caused by pain and swelling in the foot. It most oft...

Kohler disease is a rare bone disorder of the foot in children that may be the result of stress-related compression at a critical time during the period of growth. It is characterized by limping caused by pain and swelling in the foot. It most oft...

Kyphosis facts There are three main types of kyphosis: postural, Scheuermann's, and congenital. Most cases of kyphosis do not require any treatment. Physical therapy and exercise are often effective in postural a...

Eosinophilia myalgia syndrome (EMS) is associated with the ingestion of contaminated L-tryptophan, a dietary supplement often sold in health food stores. The contaminant remains unknown. It is a disease of abrupt onset causing severe, disabling, c...

Lactose intolerance is the inability to digest and absorb lactose (the sugar in milk) that results in gastrointestinal symptoms when milk or food products containing milk are consumed.        ...

Madelung's disease is a disorder of fat metabolism (lipid storage) that results in an unusual accumulation of fat deposits around the neck and shoulder areas. Adult alcoholic males are most often affected, although women and those who do not drink...

Legg-Calvé-Perthes Disease (LCPD) is one of a group of disorders known as the Osteochondroses. The Osteochondroses typically are characterized by degeneration (avascular necrosis) and subsequent regeneration of the growing end of a bone (ep...

Childhood acute lymphoblastic leukemia (ALL) is a type of cancer in which the bone marrow makes too many immature lymphocytes (a type of white blood cell). Childhood acute lymphoblastic leukemia (also called acute lymphocytic leukemia or A...

Granuloma annulare is a chronic degenerative skin disorder. The most common form is localized granuloma annulare, which is characterized by the presence of small, firm red or yellow colored bumps (nodules or papules) that appear arranged in a ring...

Lichen Planus is a rare, recurrent, itchy rash or area of inflammatory eruptions (lesions) of unknown origin characterized by shiny reddish-purple spots on the skin and gray-white ones in the mouth. The disorder may present as itchy spots on the w...

Lichen sclerosus facts Lichen sclerosus is a long-term problem of the skin that mostly affects the genital and perianal areas. Lichen sclerosus is most commonly seen in post-menopausal women. It is uncommon in men and chil...

Von Hippel-Lindau syndrome (VHL) is an autosomal dominant genetic disorder characterized by the abnormal growth of blood vessels in certain parts of the body (angiomatosis). Very small blood vessels (capillaries) "knot" together to form benign gro...

A lipoma is a slow-growing, fatty lump that's most often situated between your skin and the underlying muscle layer. A lipoma, which feels doughy and usually isn't tender, moves readily with slight finger pressure. Lipomas are usually detected in ...

Familial lipoprotein lipase (LPL) deficiency is a rare genetic metabolic disorder characterized by a deficiency of the enzyme lipoprotein lipase. The deficiency of this enzyme prevents affected individuals from properly digesting certain fats and ...

Drug-induced liver diseases are diseases of the liver that are caused by physician-prescribed medications, over-the-counter medications, vitamins, hormones, herbs, illicit ("recreational") drugs, and environmental toxins. What is the liver...

Osteogenesis Imperfecta (OI) is a group of rare disorders affecting the connective tissue and characterized by extremely fragile bones that break or fracture easily (brittle bones), often without apparent cause. The specific symptoms and physical ...

Epidermolysis bullosa (EB) is a genetic skin disorder characterized clinically by blister formation from mechanical trauma. There are four main types with additional sub-types identified. There is a spectrum of severity, and within each type, one ...

Urticaria pigmentosa is a rare skin disorder that is a localized (cutaneous) form of mastocytosis. Some clinicians suggest that urticaria pigmentosa is the childhood form of mastocytosis. Mast cells are specialized cells of connective tissue that ...

Low back pain facts Functions of the low back, or lumbar area, include structural support, movement, and protection of certain body tissues. Pain in the low back can be a result of conditions affecting the bony lumbar spin...

Familial lipoprotein lipase (LPL) deficiency is a rare genetic metabolic disorder characterized by a deficiency of the enzyme lipoprotein lipase. Deficiency of this enzyme prevents affected individuals from properly digesting certain fats and resu...

Depending on the cause, low back pain can cause a range of symptoms. The pain may be dull or sharp. It may be in one small area or over a broad area. You may have muscle spasms. Low back pain can also cause leg symptoms, such as pain, numb...

Lumbar spinal stenosis facts Lumbar spinal stenosis is a condition whereby either the spinal canal (central stenosis) or one or more of the vertebral foramina (foraminal stenosis) becomes narrowed. Lumbar spinal stenosis i...

Lung cancer facts Lung cancer is the number one cause of cancer deaths in both men and women in the U.S. and worldwide. Cigarette smoking is the principal risk factor for development of lung cancer. Passive exposure to tobac...

Lung cancer facts Lung cancer is the number one cause of cancer deaths in both men and women in the U.S. and worldwide. Cigarette smoking is the principal risk factor for development of lung cancer. Passive exposure to tobac...

Systemic lupus erythematosus (SLE) is an autoimmune disease. SLE is characterized by the production of unusual antibodies in the blood. SLE is eight times more common in women than men. The cause(s) of SLE is (ar...

Lymphangioleiomyomatosis (LAM) is a condition that occurs due to abnormal growth of smooth muscle cells, especially in the lymphatic systems and the lungs. This growth leads to the formation of cysts or holes in the lungs.  Peo...

What is male breast cancer? Men possess a small amount of nonfunctioning breast tissue (breast tissue that cannot produce milk) that is concentrated in the area directly behind the nipple on the chest wall. Like breast cancer in women, can...

What is male breast cancer? Men possess a small amount of nonfunctioning breast tissue (breast tissue that cannot produce milk) that is concentrated in the area directly behind the nipple on the chest wall. Like breast cancer in women, can...

Degos disease is an extremely rare disorder in which small and medium sized arteries become blocked (occlusive arteriopathy), restricting the flow of blood to affected areas. Degos disease usually causes characteristic skin lesions that may last f...

Mesothelioma is a rare form of cancer that affects the membrane that covers and protects various internal organs of the body (mesothelium). The mesothelium is composed of two layers of specialized cells known as mesothelial cells. One layer direct...

Mallory-Weiss syndrome refers to a tear or laceration of the mucous membrane, most commonly at the point where the esophagus and the stomach meet (gastroesophageal junction). Such a tear may result in severe bleeding from the gastrointestinal trac...

Mallory-Weiss syndrome refers to a tear or laceration of the mucous membrane, most commonly at the point where the esophagus and the stomach meet (gastroesophageal junction). Such a tear may result in severe bleeding from the gastrointestinal trac...

Malocclusion is a dental condition in which the teeth are misaligned or do not fit together properly when the jaws are closed. This can result in problems with biting, chewing, and speaking, as well as issues with the appearance of the teeth and f...

Osteopetrosis may be inherited as either a dominant or recessive trait and is marked by increased bone density, brittle bones, and, in some cases, skeletal abnormalities. Although symptoms may not initially be apparent in people with mild forms of...

Marfan syndrome is a genetic disorder that affects connective tissue, which is the material between cells of the body that gives the tissues form and strength. Connective tissue is found all over the body and multiple organ systems may be affected...

Marinesco-Sjogren syndrome (MSS) is a rare genetic disorder that affects multiple organ systems of the body. Common symptoms include difficulty coordinating voluntary movements due to degeneration (atrophy) of the cerebellum (cerebellar ataxia), c...

Melanoma is a type of skin cancer that develops in the cells that produce melanin, the pigment that gives skin its color. It is the most serious type of skin cancer and can spread to other parts of the body if not detected and treated early. Melan...

Menstrual cramps that occur in the absence of a known abnormality or cause are medically referred to as primary dysmenorrhea. Non-drug treatments for menstrual cramps include adequate rest and sleep, regular exercise (especially wal...

Mesothelioma is a rare form of cancer (malignancy) that most frequently arises from the cells lining the sacs of the chest (the pleura) or the abdomen (the peritoneum). Pleural mesothelioma is the most common form, often presenting with symptoms i...

Collagenous colitis is a rare digestive disorder that primarily affects females and typically becomes apparent during middle age. The disorder is characterized by inflammatory changes of the mucous membranes (mucosa) of the colon (colitis) and abn...

Microvascular cranial nerve palsy is a condition caused by damage to the cranial nerves due to a stroke or other vascular event. It can cause a variety of symptoms, including double vision, facial weakness, difficulty speaking, and difficulty swal...

Migraine is a type of headache that is usually characterized by a throbbing or pulsing pain on one side of the head, accompanied by nausea, vomiting, and sensitivity to light and sound. It is a neurological disorder that affects about 12% of the p...

Migraine headache is a result of specific changes within the brain. It causes severe head pain that is often accompanied by sensitivity to light, sound, or smells. Common symptoms of migraine are: Eye pain Sensi...

Erythromelalgia is a rare condition that primarily affects the feet and, less commonly, the hands (extremities). It is characterized by intense, burning pain of affected extremities, severe redness (erythema), and increased skin temperature that m...

What is mitral valve prolapse? Mitral valve prolapse (also known as "click murmur syndrome" and "Barlow's syndrome") is the most common heart valve abnormality. The condition is slightly more prevalent in women than in men. The mitral valv...

Molluscum contagiosum facts A viral infection of the skin causes molluscum contagiosum, a mild skin disease. Risk factors include direct and indirect contact with an infected person's skin. Symptoms include painl...

Peripheral neuropathy is an umbrella term that denotes a disorder of, or damage to, the peripheral nervous system. The peripheral nervous system consists of all the motor and sensory nerves that connect the brain and spinal cord to the rest of the...

Peripheral neuropathy is an umbrella term that denotes a disorder of, or damage to, the peripheral nervous system. The peripheral nervous system consists of all the motor and sensory nerves that connect the brain and spinal cord to the rest of the...

Peripheral neuropathy is an umbrella term that denotes a disorder of, or damage to, the peripheral nervous system. The peripheral nervous system consists of all the motor and sensory nerves that connect the brain and spinal cord to the rest of the...

Morton's neuroma facts Morton's neuroma is a swollen, inflamed nerve in the foot. Morton's neuroma causes a "burning" sharp pain on the bottom of the foot. Treatments for Morton's neuroma include resting the foot...

Syringomyelia is a neurological disorder characterized by the formation of a fluid-filled cyst (syrinx) within the spinal cord. This cyst may, for unknown reasons, expand during adolescence or the young adult years, destroying the center of the sp...

Mouth sores, also known as canker sores or aphthous ulcers, are small, painful lesions that develop on the inside of the mouth, including the lips, cheeks, gums, and tongue. They can be white or yellow in color and are often surrounded by a red bo...

Mucha-Habermann disease, also known as pityriasis lichenoides et varioliformis acuta or PLEVA, is a rare skin disorder. The lesions most often appear on the trunk and the arms and legs. Lesions tend to develop in small groups. Mucha-Habermann dise...

Pseudomyxoma peritonei is a rare malignant growth characterized by the progressive accumulation of mucus-secreting (mucinous) tumor cells within the abdomen and pelvis. The disorder develops after a small growth (polyp) located within the appendix...

A mucocele is a small, painless cyst that forms on the inside of the mouth, usually on the lower lip or the floor of the mouth. It is caused by a blockage of the salivary glands, which leads to the accumulation of saliva and the formation of a flu...

Multiple epiphyseal dysplasia (MED) is a rare inherited spectrum of disorders characterized by malformation (dysplasia) of the "growing portion" or head of the long bones (epiphyses). Affected individuals may have an abnormally short thighbone (fe...

Hereditary multiple osteochondromas (HMO) is a rare genetic disorder characterized by multiple benign (noncancerous) bone tumors that are covered by cartilage (osteochondromas), often on the growing end (metaphysis) of the long bones of the legs, ...

Peripheral neuropathy is an umbrella term that denotes a disorder of, or damage to, the peripheral nervous system. The peripheral nervous system consists of all the motor and sensory nerves that connect the brain and spinal cord to the rest of the...

Familial adenomatous polyposis (FAP) is a rare inherited cancer predisposition syndrome characterized by hundreds to thousands of precancerous colorectal polyps (adenomatous polyps). If left untreated, affected individuals inevitably develop cance...

Familial adenomatous polyposis (FAP) is a rare inherited cancer predisposition syndrome characterized by hundreds to thousands of precancerous colorectal polyps (adenomatous polyps). If left untreated, affected individuals inevitably develop cance...

Multiple sclerosis (MS) is a disease that causes demyelination (disruption of the myelin that insulates and protects nerve cells) of spinal nerve and brain cells. Although the exact case is unknown, multiple sclerosis is considered ...

Antley-Bixler Syndrome is a rare genetic disorder that is primarily characterized by distinctive malformations of the head and facial (craniofacial) area and additional skeletal abnormalities. For example, the disorder is typically associated with...

Munchausen syndrome is a mental disorder that is characterized by the sufferer causing or pretending to have physical or psychological symptoms in his or herself. Adults aged 20-40 years are the most likely groups to develop Munchau...

Muscle sprains and strains facts A sprain is abnormal stretching or tearing of a ligament that supports a joint. A strain is abnormal stretching or tearing of a muscle or tendon. Sprains and strains may be caused...

Myofascial pain syndrome facts Muscle pain, tenderness, and spasm are characteristics of myofascial pain syndrome. Myofascial pain syndrome typically affects muscle in asymmetric areas of the body. The precise ca...

Pain located in the neck is a common medical condition. Neck pain can come from a number of disorders and diseases and can involve any of the tissues in the neck. Examples of common conditions causing neck pain are degenerative disc disease, neck ...

Flesh-eating bacteria (necrotizing fasciitis) is a rare infection of the skin and tissues below it. It can be deadly if not treated quickly. Necrotizing fasciitis spreads quickly and aggressively in an infected person. It causes tissue dea...

Necrotizing Sarcoid Granulomatosis (NSG) is a rare granulomatous illness that primarily affects the lungs and manifests as nodular masses of confluent sarcoid-like granulomas with severe necrosis and vasculitis. It was first described in 1973, as ...

Necrotizing Ulcerative Gingivitis (NUG), also known as trench mouth, is a severe form of gum disease characterized by painful, bleeding gums, ulcers, and necrosis (death) of gum tissue. It is caused by a bacterial infection, typically associated w...

General DiscussionNeonatal lupus is a rare autoimmune disorder that is present at birth (congenital). Affected infants often develop a characteristic red rash or skin eruption. In addition, infants with neonatal lupus may develop liver di...

Renal cell carcinoma is a form of kidney cancer. Some patients with renal cell carcinoma do not have symptoms (asymptomatic). When symptoms are present, they may include blood in the urine; urine that is brown or rusty-colored; abdominal pain; wei...

Nephrogenic diabetes insipidus (NDI) is a rare kidney disorder that may be inherited or acquired. NDI is not related to the more common diabetes mellitus (sugar diabetes), in which the body does not produce or properly use insulin. NDI is a distin...

Neuroblastoma is a disease in which malignant (cancer) cells form in nerve tissue of the adrenal gland, neck, chest, or spinal cord. Neuroblastoma often begins in the nerve tissue of the adrenal glands. There are two adrenal glands, one on...

Neuropathic corneal pain is a type of chronic pain that affects the cornea, the clear outer layer of the eye. It is caused by damage to the nerves in the cornea, which can be caused by a variety of conditions, including infection, trauma, or surge...

Neuropathic pain is a pain condition that’s usually chronic. It’s usually caused by chronic, progressive nerve disease, and it can also occur as the result of injury or infection. If you have chronic neuropathic pain, it can fl...

Nocardiosis is an infectious pulmonary disease characterized by abscesses in the lungs. These abscesses may extend through the chest wall. The infection is spread through the body via the bloodstream by a microorganism called Nocardia asteroids....

General DiscussionPediatric cardiomyopathy is a rare heart condition that affects infants and children. Specifically, cardiomyopathy means disease of the heart muscle (myocardium). Several different types of cardiomyopathy exist and the s...

Henoch-Schonlein purpura is a rare inflammatory disease of the small blood vessels (capillaries) and is usually a self-limited disease. It is the most common form of childhood vascular inflammation (vasculitis) and results in inflammatory changes ...

A norovirus is a small virus that contains RNA and is surrounded by a protein coating. By sequencing the RNA, scientists have discovered that there are many different types of norovirus. Originally, strains were named based on the city in which th...

Hypertrophic cardiomyopathy (HCM) is a disease in which the heart muscle becomes...

Buerger's disease, also known as thromboangiitis obliterans, is a rare disorder that, in most cases, affects young or middle-aged male cigarette smokers. It is characterized by narrowing or blockage (occlusion) of the veins and arteries of the ext...

Tethered cord syndrome is a stretch-induced functional disorder associated with the fixation (tethering) effect of inelastic tissue on the caudal spinal cord, limiting its movement. This abnormal attachment is associated with progressive stretchin...

Ollier disease is a rare skeletal disorder characterized by abnormal bone development (skeletal dysplasia). While this disorder may be present at birth (congenital); it may not become apparent until early childhood when symptoms, such as deformiti...

Onchocerciasis, also known as African River Blindness, is a parasitic infection caused by the filarial worm Onchocerca volvulus. It is transmitted to humans through the bite of an infected blackfly. Symptoms of the infection include severe itching...

Open bite is a type of malocclusion (misalignment of the teeth) where the upper and lower front teeth do not touch when the mouth is closed. This can be caused by a variety of factors, including genetics, thumb sucking, tongue thrusting, or prolon...

Tolosa-Hunt syndrome is a rare disorder characterized by severe periorbital headaches, along with decreased and painful eye movements (ophthalmoplegia). Symptoms usually affect only one eye (unilateral). In most cases, affected individuals experie...

Tolosa-Hunt syndrome is a rare disorder characterized by severe periorbital headaches, along with decreased and painful eye movements (ophthalmoplegia). Symptoms usually affect only one eye (unilateral). In most cases, affected individuals experie...

Neuromyelitis optica, also known as Devic disease (DD), is a chronic disorder of nerve tissue characterized by inflammation of the optic nerve (optic neuritis) and inflammation of the spinal cord (myelitis). There appear to be two forms of this di...

Papillitis, also known as optic neuritis, is characterized by inflammation and deterioration of the portion of the optic nerve known as the optic disk. Also referred to as the "blind spot," the optic disk (optic papilla) is that portion of the opt...

Optic neuritis is an inflammation of the optic nerve, which is the nerve that carries visual information from the eye to the brain. Symptoms of optic neuritis include sudden vision loss, pain in the eye, and color vision changes. Optic neuritis is...

Neuromyelitis optica, also known as Devic disease (DD), is a chronic disorder of nerve tissue characterized by inflammation of the optic nerve (optic neuritis) and inflammation of the spinal cord (myelitis). There appear to be two forms of this di...

What is the oral cavity? The oral cavity and oropharynx have many parts: Lips Lining of your cheeks Salivary glands (glands that make saliva) Roof of your mouth (hard palate) Back of y...

Oral cancer is a type of cancer that develops in the tissues of the mouth or throat. It can occur in the lips, tongue, gums, floor of the mouth, roof of the mouth, or the inner lining of the cheeks and throat. Oral cancer is often linked to tobacc...

Oral cysts are fluid-filled sacs or pouches that can develop in the mouth. They can occur in various locations, including the gums, lips, tongue, and roof of the mouth. Oral cysts are typically painless and may go unnoticed until they become large...

Oral fibrosis, also known as oral submucous fibrosis, is a chronic, progressive condition that affects the mucous membranes in the mouth. It is characterized by the formation of fibrous bands of tissue in the mouth, which can lead to restricted mo...

An oral fistula is an abnormal connection or passageway that forms between two structures in the mouth, such as between the oral cavity and the skin or between the oral cavity and the nasal cavity. This can result in the leakage of saliva, food, o...

Oral hyperplasia is a condition characterized by an abnormal increase in the size of the tissues in the mouth. This can occur in the gums, tongue, cheeks, or other areas of the oral cavity. It can be caused by a variety of factors, including infla...

Oral papilloma is a benign growth or tumor that develops on the mucous membranes in the mouth. It is caused by the human papillomavirus (HPV) and typically appears as a small, painless bump or cluster of bumps. Oral papillomas are usually harmless...

Oral pyogenic granuloma, also known as pregnancy tumor or granuloma gravidarum, is a common benign growth that occurs in the oral cavity. It is characterized by a small, red, or pink, raised bump that can bleed easily. It is typically painless but...

Oral submucous fibrosis (OSMF) is a chronic, progressive condition that affects the mucous membranes in the mouth. It is characterized by the formation of fibrous bands in the oral cavity, which can lead to restricted mouth opening, difficulty in ...

Oral ulceration refers to the presence of open sores or lesions in the mouth. These ulcers can be painful and may make it difficult to eat, drink, or speak. They can occur on the lips, tongue, gums, inside of the cheeks, or roof of the mouth. Oral...

Oral vesicles are small, fluid-filled blisters that can develop on the inside of the mouth, lips, or tongue. They are often caused by viral infections, such as herpes simplex virus (cold sores) or coxsackievirus (hand, foot, and mouth disease). Or...

Osgood-Schlatter condition (formerly known as Osgood-Schlatter's disease) is a painful condition characterized by tiny, microfractures of the bony bump in the lower leg bone (tibia) where the ligament from the kneecap (patella) is inserted into th...

Osgood-Schlatter disease facts Osgood-Schlatter disease is a painful inflammation in the front of the bony leg below the knee. Osgood-Schlatter disease can cause local pain, inflammation, swelling, and calcification. ...

Osteoarthritis facts Osteoarthritis is a joint inflammation that results from cartilage degeneration. Osteoarthritis can be caused by aging, heredity, and injury from trauma or disease. The most common symptom of...

Osteoarthritis facts Osteoarthritis is a joint inflammation that results from cartilage degeneration. Osteoarthritis can be caused by aging, heredity, and injury from trauma or disease. The most common symptom of...

Osteochondritis dissecans facts Osteochondritis dissecans is a joint condition whereby a variable amount of bone and its adjacent cartilage loses its blood supply. The cause of osteochondritis dissecans is often unknown....

Osteonecrosis of the jaw (ONJ) is a rare condition in which the bone tissue in the jaw fails to heal after minor trauma, such as a tooth extraction or dental surgery, leading to the death of the bone tissue. This can result in pain, swelling, infe...

Osteopenia facts Osteopenia is decreased bone density but not to the extent of osteoporosis. This decreased bone density leads to bone fragility and an increased chance of breaking a bone (fracture). Women over the age of ...

Osteoporosis facts Osteoporosis is a condition of fragile bone with an increased susceptibility to fracture. Osteoporosis weakens bone and increases risk of bones breaking. Bone mass (bone density) decreases afte...

Ovarian cancer is a type of cancer that begins in the ovaries. The female reproductive system contains two ovaries, one on each side of the uterus. The ovaries — each about the size of an almond — produce eggs (ova) as well as the horm...

The term "ovarian cancer" includes several different types of cancer that all arise from cells of the ovary. Most commonly, tumors arise from the epithelium, or lining cells, of the ovary. These include epithelial ovarian (from the cells on the su...

Ovarian cysts facts Ovarian cysts are closed, sac-like structures within the ovary that are filled with a liquid or semisolid substance. Ovarian cysts form for numerous reasons. Pain in the abdomen or pelvis is t...

An overbite is a dental condition in which the upper front teeth overlap significantly with the lower front teeth when the mouth is closed. This can be caused by genetics, thumb sucking, or prolonged use of a pacifier. Overbites can lead to issues...

Hyperoxaluria occurs when you have too much oxalate in your urine. Oxalate is a natural chemical in your body, and it's also found in certain types of food. But too much oxalate in your urine can cause serious problems. Hyperoxaluria can b...

Paget's disease facts Paget's disease is a chronic bone disorder. Paget's disease frequently causes no symptoms. Paget's disease can cause pain in the bones or joints, headaches and hearing loss, pressure on nerv...

Different types of manual therapy, or mobilization, can be used to treat people with spinal alignment problems. For acute musculoskeletal pain, these techniques have been shown to speed recovery. In patients with musculoskeletal disorders ...

Acquired aplastic anemia is a rare disorder caused by profound, almost complete bone marrow failure. Bone marrow is the spongy substance found in the center of the bones of the body, in adults mainly the spine, pelvis, and large bones of the legs....

Idiopathic nodular panniculitis is a rare spectrum of skin disorders characterized by single or multiple, tender or painful bumps below the surface of the skin (subcutaneous nodules) that usually lead to inflammation of the subcutaneous layer of f...

Idiopathic nodular panniculitis is a rare spectrum of skin disorders characterized by single or multiple, tender or painful bumps below the surface of the skin (subcutaneous nodules) that usually lead to inflammation of the subcutaneous layer of f...

Hydrocele facts While hydroceles may occur in either gender, they are much more common in males. A hydrocele is a collection of clear fluid in a thin walled sack present in the scrotum. Hydroceles may be either o...

Pelvic Inflammatory Disease (PID) is an infection of the female reproductive organs, including the uterus, fallopian tubes, and ovaries. It is usually caused by sexually transmitted infections such as chlamydia and gonorrhea, but can also be cause...

Penile cancer is a disease in which malignant (cancer) cells form in the tissues of the penis. The penis is a rod-shaped male reproductive organ that passes sperm and urine from the body. It contains two types of erectile tissue (spongy ti...

Penile cancer is a disease in which malignant (cancer) cells form in the tissues of the penis. The penis is a rod-shaped male reproductive organ that passes sperm and urine from the body. It contains two types of erectile tissue (spongy ti...

What is a peptic ulcer? A peptic ulcer is a break in the inner lining of the esophagus, stomach, or duodenum. A peptic ulcer of the stomach is called a gastric ulcer; of the duodenum, a duodenal ulcer; and of the esophagus, an esophageal u...

What is pericarditis? The heart muscle has a tight covering that surrounds it, a lining sac called the pericardium (peri=around +cardium=heart). This sac actually has two layers. The visceral pericardium is only one cell layer thick and fi...

Pericoronitis is a condition in which the gum tissue around a partially erupted tooth becomes inflamed and infected. This most commonly occurs around the wisdom teeth, which are the last teeth to come in and often do not have enough room to fully ...

Phlebitis refers to inflammation of a vein and it can be caused by any insult to the blood vessel wall, impaired venous flow, or coagulation abnormality. Pain, swelling, redness, and tenderness are some common symptoms of phlebitis....

Phlebitis refers to inflammation of a vein and it can be caused by any insult to the blood vessel wall, impaired venous flow, or coagulation abnormality. Pain, swelling, redness, and tenderness are some common symptoms of phlebitis....

Familial hypophosphatemia is a rare inherited disorder characterized by impaired transport of phosphate and often altered vitamin-D metabolism in the kidneys. In addition, phosphate may not be well-absorbed in the intestines. The hypophosphatemia ...

Photokeratitis is a painful eye condition caused by exposure to ultraviolet (UV) radiation. It is sometimes referred to as "snow blindness" or "welder's flash." Symptoms of photokeratitis include redness, tearing, pain, and temporary vision loss. ...

Phthisis, also known as pulmonary tuberculosis, is one of the most common illnesses that humans face. It affects people of all ages, from all walks of life, and in every country.  While phthisis may affect almost every organ in...

Pilonidal cyst facts Pilonidal cysts are fluid-filled sacs that form at the top of the crease of the buttocks above the sacrum. A painful abscess can form if the cyst and the overlying skin become infected. Pilonidal cysts...

Pinworms facts Pinworm infections are caused by worm-like parasites that infect humans' intestines and rectal/anal areas. Young children and their household members are at risk for pinworm infections. Pinworms ar...

Pleurisy (pleuritis) is a health condition that occurs when the pleura, the thin layer of tissue that covers the lungs, becomes inflamed. Pleurisy (pleuritis) can be caused by a variety of things, including viruses, bacteria, and even lung cancer....

Pneumonia is an inflammatory infection that develops in the lungs. This disease fills up air sacs with fluid or pus that leads to cough with phlegm, fever, and difficulty in breathing. We inhale air from the nose or mouth that reach...

Pneumonia is a lung infection that can be caused by bacteria, viruses, or fungi. It causes inflammation in the air sacs in the lungs, leading to symptoms such as cough, fever, difficulty breathing, and chest pain. Pneumonia can range from mild to ...

Polymyalgia rheumatica and giant cell arteritis facts Polymyalgia rheumatica causes pain and stiffness in muscles and joints. Polymyalgia rheumatica is diagnosed by characteristic symptoms associated with abnormal blood te...

Preeclampsia is a pregnancy complication characterized by high blood pressure and signs of damage to another organ system, most often the liver and kidneys. Preeclampsia usually begins after 20 weeks of pregnancy in women whose blood pressure had ...

General DiscussionWolff-Parkinson-White (WPW) syndrome is a rare congenital heart disorder involving irregularities in the electrical system of the heart. In individuals with WPW syndrome, an abnormal alternate electrical pathway (accesso...

If you're a woman, you may be more familiar with the premenstrual syndrome than you'd like to be. But do you know when a problem period indicates that a visit to your doctor is in order? For most women, menstrual cycles last between 21 and...

Pernicious anemia is a rare blood disorder characterized by the inability of the body to properly utilize vitamin B12, which is essential for the development of red blood cells. Most cases result from the lack of the gastric protein known as intri...

Prostate cancer is cancer that occurs in the prostate. The prostate is a small w...

Prostate cancer is cancer that occurs in the prostate. The prostate is a small w...

Pseudogout facts Pseudogout is caused by crystals in a joint. Pseudogout causes arthritis (joint inflammation). Pseudogout can cause calcification of cartilage. The arthritis of pseudogout is diagnosed ...

Psoriatic arthritis facts Psoriatic arthritis is a chronic disease characterized by a form of inflammation of the skin (psoriasis) and joints (inflammatory arthritis). Some 10%-15% of people with psoriasis also develop inf...

Psoriatic arthritis is a chronic disease characterized by a form of inflammation of the skin (psoriasis) and joints (inflammatory arthritis). Some 10%-15% of people with psoriasis also develop inflammation of joints (psoriatic arthr...

Pulmonary alveolar proteinosis is a lung disorder characterized by a build-up of proteins, lipids, and other substances (together known as surfactants) in the lungs' air sacs, or alveoli. The alveoli are the air-holding cells in the lungs. The exc...

Pulmonary angiitis is a term used to describe a collection of disorders with both a vascular (angiitis) and granulomatous components. It means inflammation of blood vessels in the lungs.  There are five unique clinical syndromes that ...

Pulmonary hypertension is a life-threatening illness if not taken care of properly. If diagnosed, treatments can alleviate the symptoms and help you live with the disease more comfortably. High blood pressure in the arteries that run from your hea...

General DiscussionSecondary pulmonary hypertension is a disorder of the blood vessels in the lungs. It usually is the result of other lung diseases or related diseases in other organs. Affected individuals have high blood pressure (hypert...

Pleuropulmonary blastoma (PPB) is a rare childhood cancer occurring in the chest, specifically in the lungs or in the coverings of the lungs called "pleura". PPB occurs almost exclusively in children under the age of approximately 7-8 years and ra...

Lymphomatoid granulomatosis is a rare disorder characterized by overproduction (proliferation) of white blood cells called lymphocytes (lymphoproliferative disorder). The abnormal cells infiltrate and accumulate (form lesions or nodules) within ti...

Pump lung, (also known as Shock Lung), is inflammatory lung damage.  Pump lung is caused by fluid buildup in the lungs' small air sacs (called alveoli), which makes breathing very difficult. It also results in severely low bloo...

Langerhans cell histiocytosis (LCH) is a spectrum of rare disorders characterized by overproduction (proliferation) and accumulation of a specific type of white blood cell (histiocyte) in the various tissues and organs of the body (lesions). The l...

Infectious arthritis is an inflammation of one or more joints that occurs as a result of infection by bacteria, viruses or, less frequently, fungi or parasites. The symptoms of Infectious arthritis depend upon which agent has caused the infection ...

Infectious arthritis is an inflammation of one or more joints that occurs as a result of infection by bacteria, viruses or, less frequently, fungi or parasites. The symptoms of Infectious arthritis depend upon which agent has caused the infection ...

Pyogenic granuloma is a common type of non-cancerous skin growth that is typically small, red, and raised. It is also known as lobular capillary hemangioma. Pyogenic granulomas can develop on the skin or mucous membranes, such as the gums. They ar...

Reflex sympathetic dystrophy syndrome (RSDS), also known as complex regional pain syndrome, is a rare disorder of the sympathetic nervous system that is characterized by chronic, severe pain. The sympathetic nervous system is that part of the auto...

Reflex sympathetic dystrophy (RSD) facts Reflex sympathetic dystrophy (RSD) is characterized by a group of symptoms including pain (often "burning" type), tenderness, and swelling of an extremity associated with varying degrees of s...

Reflex sympathetic dystrophy syndrome (RSDS), also known as complex regional pain syndrome, is a rare disorder of the sympathetic nervous system that is characterized by chronic, severe pain. The sympathetic nervous system is that part of the auto...

Camurati-Engelmann disease is a rare genetic disorder characterized by progressive widening and malformation of the shafts of the long bones (diaphyseal dysplasia). Major symptoms may include bone pain, particularly in the legs; skeletal abnormali...

Familial dysautonomia is a rare genetic disorder of the autonomic nervous system (ANS) that primarily affects people of Eastern European Jewish heritage. It is characterized by diminished sensitivity to pain, lack of overflow tearing in the eyes, ...

Budd-Chiari syndrome is a rare disorder characterized by narrowing and obstruction (occlusion) of the veins of the liver (hepatic veins). Symptoms associated with Budd Chiari syndrome include pain in the upper right part of the abdomen, an abnorma...

General DiscussionRomano-Ward syndrome is an inherited heart (cardiac) disorder characterized by abnormalities affecting the electrical system of the heart. The severity of Romano-Ward syndrome varies greatly from case to case. Some indiv...

A root canal infection, also known as endodontic infection, occurs when bacteria enter the pulp chamber of a tooth and cause an infection. This can happen due to tooth decay, a cracked or broken tooth, or trauma to the tooth. The infection can lea...

What is the rotator cuff? The rotator cuff is the group of four tendons that stabilize the shoulder joint. The tendons hook up to the four muscles that move the shoulder in various directions. There are four muscles whose tendons f...

Rotavirus is a highly contagious virus that causes inflammation of the stomach and intestines, leading to symptoms such as severe diarrhea, vomiting, fever, and abdominal pain. It is a common cause of gastroenteritis in infants and young children,...

Rubella, also known as German measles, is a contagious viral infection that causes a mild fever and a red rash on the skin. It is typically a mild illness, but can be more serious for pregnant women, as it can cause birth defects in the developing...

Salivary gland stones, also known as sialolithiasis, are small, hard mineral deposits that form in the salivary glands. These stones can block the flow of saliva from the gland to the mouth, causing pain, swelling, and infection. Salivary gland st...

The sarcoid of boeck (sarcoidosis) is a chronic inflammatory disease that can affect any organ in the body, but most often involves the skin and lungs.  Sarcoid of boeck is characterized by the formation of small, round bumps (...

Sarcoidosis is a multisystem disorder that most often affects individuals between 20 and 40 years of age. Females appear to be affected more frequently than males. Sarcoidosis is characterized by the abnormal formation of inflammatory masses or no...