Psoriasis

Psoriasis is one of the the most ancient of repported cutaneous disorders; Celsus described it in approximately 40 AD. In the biblical era, it was considered a form of leprosy. It is said that when the French Revolutionary, Marat, was murdered by Charlotte Corday in his bath, he was soaking in the tub in order to relieve the itching of his psoriatic plaques (Leonard Feingold, personal communication). Psoriasis affects 2-4% of the Northern American and European population [1]. It is most common in Caucasians and least common in Oriental populations. African-Americans fall in-between. Psoriasis patients can be sorted into two groups based upon age of onset [1]. The Type 1 population consists of the majority of psoriasis patients. Psoriasis begins in the patients between the ages of 20 and 30. There tends to be a family history of psoriasis. In this population, there is a strong association with the major histocompatibility complex human lymphocyte antigen Cw6. Unfortunately, Type 1 psoriasis patients tend to have more severe disease ove their lifespan, which usually requires more than topical treatment. In fact, for many of these patients, by the time they have reached middle age, they have rotated through all the currently FDA-approved treatments for psoriasis. The Type 2 population of psoriasis patients gets the disease in their senior years. There tends not to be a family history of psoriasis nor a human lymphocyte antigen association. Psoriasis tends to be milder in Type 2 psoriasis patients than in Type 1 patients, that is, often topical management suffices. Approximately 75% of psoriasis patients seeking medical care can be categorized in the mild-to-moderate category. However, 25% of patients are classified as moderate-to-severe based upon criteria described in succeeding sections. Children also get psoriasis, congenital psoriasis has been reported. Psoriasis accounts for approximately 20% of a typical pediatric dermatologic practice [2].