Skin Diseases

This article will review the skin's structure and discuss, in general terms, what can go wrong. You can read about some common skin problems by searching for a LoveToKnow article on the specific disorder, or by starting with the LTK article on skin disorders.

Skin Basics

The skin is the largest organ in the human body. It has many roles. It's a protective layer that assists with temperature regulation, helps prevent dehydration by slowing down the evaporation of water from the body, and carries nerves that provide our sense of touch.

Like the rest of our bodies, skin is made up of millions of tiny cells. At the surface of the skin, flattened cells provide a tough barrier against invasion by bacteria and viruses. This top layer, called the epidermis, is designed to heal quickly if it's cut or torn. It also contains the cells responsible for skin color. These cells are called melanocytes.

Below the epidermis is a thicker, but more delicate, layer called the dermis. The dermis contains blood vessels and nerve endings. It also contains oil-producing sebaceous glands that help keep skin supple.

Last is the subcutaneous tissue. This layer contains fat cells, blood vessels, and connective tissue. Fat serves as a cushion against injury. The subcutaneous tissue also has the sweat glands, which release water to help keep the body cool.

Skin Diseases

Skin diseases happen when the skin fails to do its job, some part of the skin doesn't work properly, or something else happening in the body leads to a problem.

If the epidermis is torn or damaged, bacteria can enter the body through the skin. Usually, the immune system kills any bacteria before it can take hold. However, if it fails to do so, the result is a skin infection. Some skin infections get better on their own, but some require antibiotics. Rarely, the infection will spread to the blood or other parts of the body.

Viruses can also cause skin infections. For example, warts are a common manifestation of viral infection of the skin.

If the immune system overreacts to substances that irritate the epidermis, the result may be eczema. Eczema is a dry, itchy rash that commonly affects the hands and face. However, it can appear almost anywhere on the body. Other immune problems can cause other disorders in the skin.

Many skin diseases begin with specific elements of the skin. The melanocytes may fail, leaving white patches of skin where no color-producing cells are left. Blood vessels dilating too easily may be the cause of rosacea, a reddening of the skin which usually affects the face. Too much oil production can lead to acne. The sweat glands may be either over-active or under-active.

Genetic Disorders

Many skin diseases have a genetic or hereditary element. Some people have a missing or damaged bit of their genetic code, so that their skin cells don't work properly. For example, the skin cells may reproduce too quickly. This usually leads to a rough, scaly rash which may cover the entire body.

In some cases the cells fail to make an important protein or don't make it correctly. The layers may not stick together, so that even minor injury leads to large blisters as the layers separate. Or, there may be other problems with the workings of the skin.

For More Information

The first step in diagnosing and treating a skin disorder is to seek a doctor's care. Many rashes look alike. Your doctor can help you figure out exactly what you have and how to treat it.

The following web sites have extensive information on skin diseases:

• Family Doctor.org. The web site of the American Academy of Family Physicians has a large section on skin problems.
• Health Topics at the National Institute of Arthritis and Musculoskeletal and Skin Disorders. NIAMS has detailed Q&A's and fact sheets.
• Medline Plus from the National Institutes of Health. A Medline Plus search will direct you to many helpful sites.

You can see photos of many common skin disorders here at LoveToKnow Skin Care:

• Pictures of Skin Disorders