Pityriasis rubra pilaris

[Julian]

Pityriasis rubra pilaris is a rare chronic skin disorder that causes thickening and yellowing of the skin, including the palms and soles, and red, raised bumps. The bumps may merge together to form red-orange, scaly patches (plaques) with areas of normal skin in-between.
The cause of pityriasis rubra pilaris is unknown.
The two most common forms of the disorder are

Juvenile classic
Adult classic

The juvenile classic form of pityriasis rubra pilaris is inherited and begins in childhood. The adult classic form of pityriasis rubra pilaris does not seem to be inherited and begins in adulthood.
Other nonclassic forms exist in both age groups. Sunlight, human immunodeficiency virus (HIV) infection or another infection, minor trauma, or an autoimmune disorder may trigger a flare-up.