Psoriasis seems to be an inherited disorder, and it appears to be related to the immune or inflammatory response . It is most commonly seen on the trunk, elbows, knees, scalp, skin folds, or fingernails, but it may affect any or all parts of the skin. Normally, skin takes about a month for its new cells to move from the lower layers of skin up to the surface. In psoriasis, this process takes only a few days, resulting in build-up of dead skin cells and formation of thick scales . Psoriasis is not contagious.
None is known.
Minimize flare-ups by avoiding aggravating factors. The diagnosis is usually based on the appearance of the skin. A skin biopsy or scraping and culture of skin patches may be needed to rule out other disorders. A blood test for HLA antigens may be positive. Treatment is focused on control of the symptoms and prevention of secondary infections .