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Pityriasis Rubra Pilaris


Shinjita Das

, MD, Harvard Medical School

Last full review/revision Apr 2020| Content last modified Apr 2020
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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.

Symptoms of Pityriasis Rubra Pilaris

Symptoms of pityriasis rubra pilaris include pink, red, or orange-red scaly patches that can develop on any part of the body and are usually itchy. The skin can become thick and yellow.

Diagnosis of Pityriasis Rubra Pilaris

  • A doctor's evaluation

  • Skin biopsy

Doctors base the diagnosis of pityriasis rubra pilaris on how the scales and plaques look and where they appear on the body.

Doctors sometimes take a sample of skin tissue and examine it under a microscope (biopsy) to rule out other disorders (such as seborrheic dermatitis in children and psoriasis).

Treatment of Pityriasis Rubra Pilaris

  • Drugs applied to the skin

  • Drugs taken by mouth

  • Phototherapy

Treatment of pityriasis rubra pilaris is very difficult. Symptoms of the disorder may be lessened, but the disorder itself can almost never cured. Classic forms of the disorder go away slowly over 3 years, whereas nonclassic forms last much longer.

To reduce scaling, doctors may give skin moisturizers (emollients) or have people apply lactic acid under a dressing that keeps air away from the skin (occlusive dressing), followed by corticosteroids applied to the skin. Vitamin A taken by mouth may be effective. Acitretin or methotrexate taken by mouth is an option when treatments applied to the skin are not helping.

Phototherapy (exposure to ultraviolet light) and drugs that weaken the immune system, such as tumor necrosis factor (TNF)-alpha inhibitors, cyclosporine, mycophenolate mofetil, azathioprine, and oral corticosteroids, have also been used.

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Test your knowledge

Psoriasis is a common chronic disease affecting 1 to 5% of the population worldwide. It causes distinctive raised, red patches with silvery scales. A border between the patch and normal skin is known as “psoriatic plaque.”  Which of the following is the reason these patches of plaque form?
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