Pityriasis rubra pilaris is a rare skin condition that results in inflammation and skin shedding, according to Healthline. It affects men and women equally, and patients may experience the condition in localized areas or over the entire body.
The most common form of pityriasis rubra pilaris is classical adult onset, and while symptoms normally go away after a few years, they occasionally, albeit rarely, return later in life, notes Healthine. Some patients suffer from atypical adult onset pityriasis rubra pilaris, in which symptoms may last for more than 20 years. Children may suffer from classical juvenile onset pityriasis rubra pilaris, in which symptoms go away in less than a year but may return, or atypical juvenile onset pityriasis rubra pilaris, which may be inherited and may last indefinitely. Children with the circumscribed juvenile onset form of the condition show symptoms before they reach puberty, normally on the palms, soles of the feet, knees and elbows.
People with HIV-associated pityriasis rubra pilaris suffer from symptoms that are difficult to treat, reports Healthline. Doctors do not know the exact cause of pityriasis rubra pilaris, as of 2015, though some forms are inherited and others may be associated with conditions such as skin cancer. Some research indicates that an abnormality in the way the body processes vitamin A and atypical immune system responses can lead to the condition, though scientists must perform more research to verify these causes.