Long-term ustekinumab treatment for refractory type I pityriasis rubra pilaris

Pityriasis rubra pilaris is a rare, chronic erythematous squamous disorder of unknown etiology. The disease is characterized initially by small follicular papules that coalesce into yellowish pink scaly plaques, palmoplantar keratoderma, diffuse furfuraceous scale of the scalp, and frequent progression to exfoliative erythroderma. Generally it is difficult to discern pityriasis rubra pilaris from other skin conditions but key-clinical features help in the diagnosis such as "islands" of spared skin within generalized erythroderma, follicular keratotic plugs, and an orange hue of the involved skin. Treatment options include topical vitamin D analogues, keratolytics, systemic acitretin, methotrexate, cyclosporine, azathioprine, fumaric acid esters, phototherapy, and anti-TNFα agents. Cases, of pityriasis rubra pilaris, successfully treated with a short-course ustekinumab therapy, have been reported.