ABSTRACT
DEFINITION AND CLINICAL FEATURES Psoriasis is a common chronic inflammatory papulosquamous eruption with a prediliction for the extensor aspects of limbs and scalp. Both sexes are equally affected and there is a bimodal distribution of the age of onset which peaks in adolescence and middle age. The severity of disease may vary with time and a range of clinical patterns are recognized. Family studies indicate a strong genetic component, and precipitating or exacerbating factors include trauma (Köbner phenomenon) (59), streptococcal infection, various drugs (e.g. lithium, beta-blocking agents, antimalarials), stress, alcohol, and smoking.
