Skin Disorders

A boil is a painful swelling of the skin caused by a bacterial infection in a hair follicle. Technically called furuncles, boils usually develop in hairy parts of the body that are exposed to friction and pressure. They appear most often on the face, scalp, back of the neck, armpits, and buttocks, and are more common in men than in women.

Corns are small, round mounds of firm, dead skin that usually form over bony areas of the toes. Calluses are thickened areas that most often develop on the balls and heels of the feet and on the hands. Both are caused by friction or pressure against the skin, commonly the result of wearing shoes or socks that do not fit properly or engaging in work or sports activities that involve constant rubbing and pressure. In some cases, they are caused by arthritis or deformities in the structure of bones.

Dandruff is a form of seborrheic dermatitis, an inflammatory condition in which dead scalp cells flake off leaving telltale signs on the shoulders and clothing. More severe cases also affect the skin around the nose, behind the ears, or in the armpits or genital area.

Dermatitis is the general term for any inflammation of the skin. Typical symptoms include scaling, itching, flaking, thickening, and changing coloration. Among the many causes are various types of allergic responses, bacterial and viral infections, chemical damage, insect bites, poor circulation, vitamin deficiencies, and stress.

At some time, almost all babies develop diaper rash, which is confined to the skin covered by a diaper. The affected area is dotted with small, pimple-like bumps that may become scaly or crusty. Sometimes the sores ooze and have an unpleasant odor.

Eczema refers to a wide variety of skin conditions. In general, lesions that are red, blistering, oozing, scaly, brownish, thickened, and itchy may all be considered eczema. The term is often used interchangeably with dermatitis, which causes similar lesions, but unlike eczema, dermatitis usually has an identifiable external cause.

Heat rash, or prickly heat, consists of clusters of tiny blisters filled with perspiration. It forms when pores become blocked and prevent the sweat glands from releasing perspiration, or when heat and humidity exceed the ability of the sweat glands to cool the body. The rash itches but does not become inflamed. It usually develops in the armpits and groin, and sometimes also on the chest, waist, and back.

Hives, an allergic skin disorder, are raised round pink or red lesions with flat tops. They are itchy and warm to the touch. More severe hives, called angioedema, tend to be larger and linked to one another; they also penetrate more deeply into the skin. In rare cases, hives can develop in the mouth and throat, obstructing breathing or heralding a life-threatening anaphylactic reaction. Most often, hives are caused by food allergies, with the most frequent culprits being chocolate, shellfish, nuts, eggs, strawberries and other fruits, as well as food preservatives, dyes, and other food additives. Some people develop hives after eating even a minute amount of the offending food, while others break out only when they overindulge in it.

From time to time, everyone develops an itching sensation, which prompts an instinctive desire to scratch. Most itches are caused by localized skin conditions, that range from insect bites or dry skin, to allergic reactions or rashes resulting from chickenpox, athlete's foot, and other infectious diseases. A maddening and persistent itch characterizes some skin disorders, especially eczema, and stress can either produce or aggravate it.

Pityriasis rosea is a common, relatively short-lived skin disorder exhibiting a scary rash of symmetrical pink patches. The underlying cause is unknown, but an unidentified virus is believed to be the culprit. Even so, it is not contagious.

Pityriasis typically occurs during the spring and autumn months and affects mostly adolescents or young adults. It begins with a large pink spot -- called a herald or mother patch -- on the chest or back. (This initial patch is often mistaken for ringworm or an insect bite.) Within a week or two, other, smaller pink spots appear over the trunk, upper arms, and legs. The spots may also occur on the neck, but they rarely spread to the face. The rash on the trunk sometimes resembles an evergreen tree with drooping branches. On individuals who are suntanned, the rash may be confined to unexposed areas of the body, such as the breasts, armpits, buttocks, and pubic area.

Psoriasis is a recurrent disorder in which patches of skin become red and covered by dry, silvery scales. About 5 million Americans have the condition, which usually develops during young adulthood through late middle age. Although psoriasis is seldom serious medically, the unsightly lesions can lead to emotional problems.

Rosacea is a chronic disorder of the facial skin that produces skin swelling and inflammation, along with small blisters and telangiectasia, clusters of tiny blood vessels just under the skin surface. It usually appears after age 30 and affects women, especially those with light skin and fair hair, three times more often than men. The disease is more severe in males, however.

(Fibroblastic Cutaneous Overgrowth; Hypertrophic Scars)

Whenever skin is damaged -- due to an accidental cut, surgery, burn, or other trauma -- scar tissue forms as part of the healing process. Such tissue is composed of special cells called fibroblasts, which make the affected area stronger, thicker, and tougher than usual and cause it to stand out from surrounding skin.

Usually, such scars tend to shrink slightly with age. becoming less noticeable or even invisible
Sometimes, however, a scar continues to grow even after an injury has healed. It forms a keloid, a growth composed of connective tissue, which is raised, shiny, and pink or red in color. In some cases, keloids resemble small tumors; in others, they have claw-like extensions around the growth. The keloid itself may be tender or itchy.

At least 50 different skin growths are classified as warts. All are caused by strains of the human papillomavirus (HPV), which infect the skin's epithelial cells, prompting them to multiply abnormally fast. The virus can be passed readily from person to person by direct contact.