Psoriasis is a common and recurring condition in which the skin develops red patches of various sizes, covered with dry, silvery scales. Most often, it affects the scalp, the trunk of the body and the outer side of the arms and legs, especially the elbows and knees. The palms and soles may also be involved. Fortunately the face is usually spared. It is usually a lifelong problem. There is no cure for psoriasis, but recent therapeutic advances have given new hope to patients who suffer from this disease.