Psoriasis (suh-RYE-uh-sihs) is a group of skin disorders that may vary widely in symptoms, severity, and location. The condition results when skin cells reproduce much faster than they can be shed, leading to an excess buildup of dead skin. It's possible for a person to have more than one type of psoriasis at the same time, and over the years, the condition may periodically retreat, then reappear. The most common form of psoriasis is known as plaque psoriasis, which causes raised welts or lesions on the skin that are coated with a silvery white scale. Plaque psoriasis can show up anywhere, but is usually found on the scalp, knees, elbows, or trunk. Another type, pustular (PUHST-you-lahr) psoriasis, is marked by non-contagious, pus-filled blisters. Sometimes the blisters are limited to the hands and feet, or they may spread over the body. In erythrodermic (eh-rith-roe-DERM-ihk) psoriasis, the skin reddens and sloughs off, causing extreme itching and soreness. Another form called guttate (GUHT-tate) psoriasis causes tiny red dots on the arms, legs, or trunk. While most psoriasis lesions are raised, inverse psoriasis usually appears as a smooth, wine-like stain in creased areas such as the armpits or groin.