Pityriasis Rubra Pilaris

By Shinjita Das, MD, Clinical Instructor;Physician, Department of Dermatology, Harvard Medical School;Massachusetts General Hospital

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Psoriasis and Scaling Diseases
Psoriasis
Lichen Planus
Lichen Sclerosus
Parapsoriasis
Pityriasis Lichenoides
Pityriasis Rosea
Pityriasis Rubra Pilaris

Pityriasis rubra pilaris is a rare chronic disorder that causes hyperkeratotic yellowing of the skin, including the trunk, extremities, and, particularly, the palms and soles. Red follicular papules typically merge to form red-orange scaling plaques and confluent areas of erythema with islands of normal skin between lesions.

The cause of pityriasis rubra pilaris is unknown.

The 2 most common forms of the disorder are

Juvenile classic (characterized by autosomal dominant inheritance and childhood onset)
Adult classic (characterized by no apparent inheritance and adult onset)

Atypical (nonclassic) forms exist in both age groups. Sunlight, HIV or another infection, minor trauma, or an autoimmune disorder may trigger a flare-up.

Treatment

Symptom relief (eg, with emollients, topical lactic acid and topical corticosteroids, or oral retinoids)

Treatment of pityriasis rubra pilaris is exceedingly difficult and empiric. The disorder may be ameliorated but almost never cured; classic forms of the disorder resolve slowly over 3 yr, whereas nonclassic forms persist. Scaling may be reduced with emollients or 12% lactic acid under occlusive dressing, followed by topical corticosteroids. Oral vitamin A may be effective. Oral acitretin (a retinoid) or methotrexate is an option when a patient is resistant to topical treatment.

Phototherapy, immunomodulatory agents (biologics), cyclosporine, mycophenolate mofetil, azathioprine, and corticosteroids have also been used (1).