The cause of
psoriasis is not fully understood. There are two main hypotheses about the process that occurs in the development of the disease. The first considers psoriasis as primarily a disorder of excessive growth and reproduction of skin cells. The problem is simply seen as a fault of the
epidermis and its
keratinocytes. The second hypothesis sees the disease as being an
immune-mediated disorder in which the excessive reproduction of skin cells is secondary to factors produced by the
immune system.