Basically it is a disorder of epidermal cell proliferation, characterized clinically by excessive peeling skin and lesions in the form of localized pruritic and hyperkeratotic plaques on the trunk, joints and scalp. The plates are red, symmetrical, circumscribed, thick-edged and well defined, covered with pearly white scales, overlapping, abundant and easily removable.
Unknown until very recently, Dr. Milstein has determined the cause of psoriasis as a combination of hereditary factors, environmental and psychosomatic, that determine an abnormal immune response, and cause the acceleration of cellular metabolism of the dermis.
While the new skin cells take about 1 month normal to migrate from the deeper layers of skin to the surface, in psoriasis this process takes just a few days, so that there is a constant turnover of cells, dead cells peel slowly and may not persist into large flakes and typical psoriatic keratosis.