What Is Psoriasis?

Psoriasis is an autoimmune disease that appears on the skin. It occurs when the immune system mistakes the skin cells as a pathogen, and sends out faulty signals that speed up the growth cycle of skin cells. Psoriasis is not contagious.^[1] However, psoriasis has been linked to an increased risk of stroke. ^[2] There are five types of psoriasis: plaque, guttate, inverse, pustular and erythrodermic. The most common form, plaque psoriasis, is commonly seen as red and white hues of scaly patches appearing on the top first layer of the epidermis (skin). Some patients, though, have no dermatological symptoms.

The cause of psoriasis is not fully understood, but it is believed to have a genetic component and local psoriatic changes can be triggered by an injury to the skin known as the Koebner phenomenon,^[5] see Koebnerisin. Various environmental factors have been suggested as aggravating to psoriasis, including stress, withdrawal of systemic corticosteroid, as well as other environmental factors, but few have shown statistical significance.