Flexural psoriasis of an armpit. Patches (plaques) of reddened skin in an armpit of a patient with flexural psoriasis, a form of psoriasis that occurs in skin folds. 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 triggered by many factors including emotional stress, some infections or certain drugs, although in many cases there is no obvious cause. Emollient creams, phototherapy and drug treatments can be used if the cause is unknown.