Treatment of pityriasis rubra pilaris type I: a systematic review

Pityriasis rubra pilaris (PRP) is an uncommon papulosquamous inflammatory disease of the skin, which may progress to erythroderma. The diagnosis is based on both clinical and histopathological findings. There are numerous treatment options in the literature, but often reported as unsuccessful. To summarize the therapy of type I PRP in a systematic manner. We performed a systematic search following the PRISMA Guidelines based on PubMed, Web of Science, and Medline databases using the term 'pityriasis rubra pilaris treatment' (in German and English) on human subjects, published between 1997 and 2017, documenting therapy for PRP type I. A total of 449 records were identified; 148 full-text articles were assessed for eligibility and 105 articles were included in the qualitative synthesis. We identified mainly individual case reports, a few retrospective studies, and small case series. No randomized controlled trials were found. Treatment options included topical and systemic agents, and physical modalities. Based on our review, we suggest a continuous topical treatment and, when appropriate, in combination with phototherapy. As first-line therapy, we recommend a retinoid, and as second-line, a combination of retinoid and methotrexate (considering the patient's condition and side effects), azathioprine, or cyclosporine A. Biologicals can be used as third-line therapy. In case of treatment failure, biologicals can be combined with a retinoid, methotrexate, or cyclosporine A. Randomized controlled clinical trials are needed in order to provide an evidence-based high-quality standardized treatment for patients with PRP type I.