MONDO_0100017 (pityriasis rubra pilaris) is a group of skin conditions that cause constant inflammation and scaling of the skin. People with PRP have reddish, scaly patches that may occur everywhere on the body, or only on certain areas. Some people with PRP also develop thickened skin on the underside of the hands and feet (palmoplantar keratoderma), various nail abnormalities, and/or thinning of the hair. There are several types of PRP classified by age when symptoms begin, body areas involved, and whether other conditions are present. This condition occurs in adults (adult onset PRP) as well as children (juvenile onset PRP).