Psoriasis

Epidemiology

Rates of psoriasis in the United States tend to be higher in Caucasians than other ethnicities. Furthermore, about 40 percent of psoriatics have a first-de-gree relative with the disease. In studies of twins, a common method for testing genetic predisposition to diseases, psoriasis is also more prominent among identical twins than fraternal ones. Environmentally, psoriasis tends to be more common among those who smoke tobacco or drink alcohol. Increased levels of stress have also been implicated in severity of the disease.

Types of Psoriasis

There are four general types of psoriasis:

• Plaque psoriasis: Lesions are usually raised from the skin, red, and have distinct borders. Lesions also typically involve extensor surfaces (elbows and shins) as well as the scalp.
• Pustular psoriasis: This is the most severe form and is associated with scaling and pustules (bumps on the skin filled with pus). Typically, patients with pustular psoriasis also have abnormalities in liver function.
• Inverse psoriasis: Lesions are typically located within intertriginous areas (areas within folds of the skin). This type is not usually associated with scaling.
• Nail psoriasis: Typically associated with another form of psoriasis. This type is associated with pitting of the nails, a helpful diagnostic tool for healthcare providers. Nails may also have an area of tan-brown pigmentation that resembles the color of unused motor oil.

Psoriasis and the Connection with HIV and Psoriasis

Psoriasis is a disease that in general, tends to be more common in those who have an autoimmune disorder, or a disease in which the body mounts an immune response against itself. Psoriasis is also more common in those who have other diseases that suppress the immune system. Psoriasis in patients afflicted with HIV is particularly severe. There is also a genetic connection, as both diseases are apparently localized to a similar area on a locus of genetic material. Psoriasis is also intimately related to arthritis, as many psoriatics also suffer from arthritis. In short, psoriasis is a disease that is heavily influenced by the integrity of the immune system's ability to mount an appropriate attack.

Treatments

Treatment for psoriasis generally depends on the severity of the condition, ranging from topical emollients and creams to systemic agents that alter the immune response. Topical emollients and skin lotions are indicated for mild cases to limit scaling and redness. Topical corticosteroids are effective for plaque psoriasis, with the mode of administration (solution, cream, gel, foam) depending on the affected area. Calcipotriene (Dovonex®) is an agent that limits proliferation of keratinocytes, cells that shed off and contribute to scaling. Methotrexate, a drug that limits cell division in targeted cells, is an old drug that has been used for years, and is useful for cases of psoriatics who also have arthritis. Other immunomodulating drugs, drugs that alter the immune system, are currently being tested, including antineoplastic (anticancer) agents.

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