Psoriasis has existed for centuries. Typical signs of psoriasis have been found on mummified bodies in tombs dating from the beginning of the Christian era. It is known to have been confused with leprosy for hundreds of years, leading to many people with psoriasis being ostracized in the Middle Ages.
Psoriasis gets its name from the Greek word psōra meaning "itch," psoriasis is a chronic, non-contagious condition characterized by inflamed lesions covered with silvery-white scabs of dead skin. As a result, itchy, scaly red patches appear, often on the elbows, hands, feet, and scalp, but they can show up on other parts of your body. Usually, what happens is new skin cells take about a month or so to move from the deepest skin layer where they're produced, to the surface where they die and flake off. With psoriasis, the entire skin cell life cycle takes only days. Because the body can't shed old skin as rapidly as new cells are rising to the surface, raised patches of dead skin develop on the arms, back, chest, elbows, legs, nails, folds between the buttocks, and scalp.