Psoriasis of the hand. Close-up of the hand of an 18-year-old male patient affected by chronic plaque psoriasis. Psoriasis is a condition in which skin cells are produced much faster than normal. The body cannot shed the cells fast enough, resulting in patches (plaques) of scaly, thick skin, which are often itchy and may become infected. Psoriasis is thought to be triggered by emotional stress, some infections or certain drugs, although in many cases there is no obvious cause. Treatment is aimed at the cause if it is known. If it is not, emollient creams, phototherapy and drug treatments can be used.