Acanthosis nigricans is a skin condition characterized by areas of dark, velvety discoloration in body folds and creases. The affected skin can become thickened. Most often, acanthosis nigricans affects your armpits, groin and neck. The sk...

Seborrheic Keratosis is a skin disorder usually characterized by discolored lesions that appear to be "stuck on" the skin surface. Warts may appear and skin is often oily or greasy. These skin lesions are sometimes mistaken for cancerous growths a...

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 ...

Acne (acne vulgaris, common acne) is a disease of the hair follicles of the face, chest, and back that affects almost all teenagers during puberty -- the only exception being members of a few primitive Neolithic tribes living in isolatio...

Alkaptonuria is an inherited condition that causes urine to turn black when exposed to air. Ochronosis, a buildup of dark pigment in connective tissues such as cartilage and skin, is also characteristic of the disorder. This blue-black pigmentatio...

Hairy tongue is an uncommon, benign condition that is also known as black hairy tongue or lingua nigra. It is characterized by abnormal elongation and blackish or dark brownish discoloration or "staining" of the thread-like elevations (filiform pa...

Blue rubber bleb nevus syndrome (BRBNS) is a rare blood vessel (vascular) disorder that affects the skin and internal organs of the body. Multiple distinctive skin lesions are usually characteristic of this disorder and are often present at birth ...

Cyst facts Cysts are closed sac-like or capsule structures that may be filled with semisolid material, gaseous material, or liquid. There are several causes of cysts, including genetic, infectious, and other causes that resu...

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...

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)...

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...

Alkaptonuria is a rare genetic metabolic disorder characterized by the accumulation of homogentisic acid in the body. Affected individuals lack enough functional levels of an enzyme required to breakdown homogentisic acid. Affected individuals may...

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...

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...

Alkaptonuria is a rare genetic metabolic disorder characterized by the accumulation of homogentisic acid in the body. Affected individuals lack enough functional levels of an enzyme required to breakdown homogentisic acid. Affected individuals may...

Alkaptonuria is a rare genetic metabolic disorder characterized by the accumulation of homogentisic acid in the body. Affected individuals lack enough functional levels of an enzyme required to breakdown homogentisic acid. Affected individuals may...

Though they're not cancerous, sebaceous cysts can be irritating. A sebaceous cyst is a small lump or bump under the skin. This type of cyst is not cancerous. They are most often found on the face, neck, upper back, and upper chest,...

Stretch mark facts The medical name for stretch marks is striae distensae. Stretch marks are very common. Stretch marks rarely are a sign of a significant medical problem. Stretch marks are generally pa...

Warts are small, self-limited tumors caused by human papillomavirus (HPV) infection. Types of warts include common warts, flat warts, plantar warts, periungual warts, and filiform warts. Warts typically disappear on their ...