ABSTRACT
DEFINITION AND CLINICAL FEATURES Psoriasis is a papulosquamous inflammatory skin disorder. Despite intense investigation, the cause of psoriasis is not well understood. It would appear that there is a genetic tendency toward psoriasis, but an environmental exposure or ‘trigger’ is necessary for disease onset. While older references state that psoriasis is a disorder of epidermal proliferation, it is now understood that the disease is chiefly a consequence of aberrant T-cell function.
