Skin Disorders - Description
Dermatitis is a general term used to describe inflammation of the skin. Most types of dermatitis are characterized by a pink or red rash that itches. The most common form of dermatitis is contact dermatitis. This condition is caused by an allergic reaction to some material. It can occur on any part of the body, but appears most often on the hands, feet, and groin.
Contact dermatitis usually does not spread from one person to another. In some cases, however, it can be transferred from one part of the body to another. Poison ivy is an example. A person infected with poison ivy may first start scratching on the hands. But the infection may then be transferred to other parts of the body.
Other forms of dermatitis are less common. They include:
- Statis dermatitis, which is characterized by scaly, greasy-looking skin. This form most commonly affects the lower legs and ankles.
- Nummular dermatitis, which affects the hands, arms, legs, and buttocks. The condition occurs most commonly in men and women over the age of fifty-five.
- Atopic dermatitis, which usually occurs in early childhood. It is sometimes called infantile eczema. It usually occurs on the face, inside the elbows, and behind the knees.
- Seborrheic dermatitis (pronounced SEB-uh-REE-ick dur-muh-TY-tuhss), which may be dry or moist. It causes the formation of greasy scales and yellow crusts. The body parts most affected are the scalp, eyelids, face, ears, underarms, breasts, and groin.
Psoriasis is a chronic (long-lasting), non-contagious disease characterized by open sores in the skin that become covered with silvery-white scabs.
Psoriasis affects about four million Americans. The disease may develop at any age. About 10 to 15 percent of all cases are first diagnosed during childhood. The average age of diagnosis is twenty-eight.
Psoriasis occurs when skin cells start to grow very rapidly. Normally, the rates at which skin cells grow and die off are about the same. As old skin cells die, new ones replace them. In the case of psoriasis, new skin cells grow much more rapidly than old cells die off. As a result, new skin cells push older dead skin cells upwards. They form patches of dead skin on the arms, back, chest, elbows, legs, nails, and scalp. These patches are the scabs that are characteristic of psoriasis.
Vitiligo is a condition in which smooth, white patches develop on the skin. It is caused when melanocytes die off. Melanocytes (pronounced MELL-uh-no-sites) are skin cells that give skin their color.
Vitiligo affects 1 to 2 percent of the world's population. It occurs equally among men and women. The disorder can first appear at any age. In about half of all cases, however, it starts before the age of twenty.
Vitiligo may appear as one or two well-defined white patches on the skin. Or it may cover large portions of the body. People with vitiligo often have other medical problems also, such as eye disorders, thyroid disease, diabetes mellitus, and pernicious anemia (see entries on visions disorders, diabetes mellitus, and anemias).
- Allergic reaction:
- A series of events initiated by the immune system against substances that are normally harmless to the body.
- A condition that continues for a long period of time.
- Immune system:
- A network of organs, tissues, cells, and chemicals designed to fight off foreign invaders, such as bacteria and viruses.
- A specialized skin cell that produces melanin, a dark pigment (color) found in skin.
- A spotted pink or red skin condition that may be accompanied by itching.
- A category of naturally occurring chemicals that are very effective in reducing inflammation and swelling.
- Ultraviolet (UV) light:
- A naturally occurring part of ordinary sunlight that may, under some circumstances, have beneficial effects in curing certain medical disorders.