Treatment of refractory adult-onset pityriasis rubra pilaris with TNF-alpha antagonists: a case series

Background Pityriasis rubra pilaris (PRP) is a rare inflammatory dermatosis with frequent clinical presentation as erythroderma. Conventional systemic treatment is often unsatisfactory and limited by long-term toxicity. The use of tumour necrosis factor (TNF) antagonists has been reported previously in single cases, but lacking long-term follow-up or comparison between different biological agents. Objectives To assess the long-term efficacy and safety of TNF-alpha antagonist, infliximab and etanercept, either in monotherapy or in combination therapy of severe, refractory adult-onset PRP. Methods Seven patients of adult-onset PRP, six newly diagnosed type-I and 1 type-II, which were resistant or ineligible to conventional systemic treatment, received a single course of infliximab or etanercept therapy, alone or in combination with low-dose acitretin (> 0.25 mg/kg/daily). After complete remission and treatment discontinuation, a follow-up period of 12 months was evaluated for relapses. Results Six patients obtained complete remission after a single course of anti-TNF-alpha therapy: mean therapy duration was 19.3 weeks (range 6-48 weeks). All patients obtained significant clearing (> 75% of body surface area) of skin lesions at week 12. Two patients with marked keratoderma developed localized disease recurrence during treatment. During follow-up, only a single patient, affected by type II PRP, had disease relapse. Conclusions Both TNF-alpha antagonists proved successful for the treatment of refractory, adult-onset PRP, yielding complete and persistent clinical responses in type-I PRP. Infliximab was associated with a more rapid onset of action, while treatment duration was comparable with etanercept. PRP type II warranted long-term therapy and showed relapse after drug discontinuation.