Types of psoriasis

Several types of psoriasis have been identified, although a person usually has only one type at a time. According to the U.S. National Institutes of Health, variations include:

• Plaque psoriasis . The most common type, it consists of inflamed lesions that are red with a silvery scale covering. Typical locations for this type of psoriasis are the lower back, knees, elbows and scalp.
• Guttate psoriasis . Often triggered by upper respiratory infections and sometimes by medications, this type features small, red spots on the skin, usually on the trunk or limbs.
• Inverse psoriasis . This form appears in areas where the skin folds, such as the armpits, under breasts and near the genitals, and may result from friction or sweating. Lesions are bright red and shiny and often itch.
• Pustular psoriasis . Characterized by blisters containing pus that's not infectious, this form can be triggered by such things as medications, stress and infections. It might show up on the hands or feet, or it might cover large areas of the body.
• Erythrodermic psoriasis . With this type, the bright red and scaly skin is usually widespread, often seriously painful and itchy. Some medications and sunburn are known triggers. Severe cases can require hospitalization.