Psoriasis does not cause scarring or hair loss, and infrequently affects the face. Its exact cause is unknown but the result is skin which grows about seven times more quickly and thickly than usual. It is thought to be due, at least in part, to an abnormal immune reaction against some component of the skin. The extent of psoriasis varies, and fluctuates even without treatment. Psoriasis can be characterized by degree of severity .
Dermatologists diagnose psoriasis by examining the skin, nails, and scalp.
They may need to take a skin biopsy to examine under the microscope. Treatment is based on a patient's health, age, lifestyle, and the severity of the psoriasis. The doctor may prescribe medications to apply on the skin containing cortisone-like compounds, synthetic vitamin D, tar, or anthralin. These may be used in combination with natural sunlight or ultraviolet light. Sunlight exposure helps the majority of people with psoriasis but it must be used cautiously.