Psoriasis is a chronic non-infectious inflammatory disease of the skin characterized by well-defined erythematous plaques bearing large, adherent silvery scales. Plaque pattern is the most common type. Lesions are well marcated and range from a few millimeters several centimeters in diameter. Guttate pattern is usually seen in children and adolescents and may be the first sign of the disease often triggered by tonsillitis. Scalp is often involved. Involvement of the nails is common with thimble pitting onycholisis. Flexural psoriasis is commonest in women and in the elderly. Palm psoriasis may be hard to recognize as its lesions are often poorly demarcated and barely erythematous. Napkin psoriasis spread outside the napkin area may give the first clue to a psoriatic tendency in an infant
