Psoriasis of man's elbow. The red lesion is a well defined area of skin covered with coarse, silvery scales. The elbows and knees are commonly involved and lesions are usually symmetrically distributed. Coal tar and dithranol are used for moderately severe cases. Other applications include emollients, keratolytic and corticosteroid drugs. In severe cases, psoralen drugs with phototherapy, retinoid drugs and methotrexate may be used. Psoriasis may be disfiguring enough to require psychological counselling and concealment therapy.