Ustekinumab treatment of pityriasis rubra pilaris: A report of five cases.

Pityriasis rubra pilaris (PRP) is a rare, chronic, inflammatory skin disease of unknown etiology. Patients refractory to conventional therapies have been treated successfully with biologic drugs such as anti-tumor necrosis factor agents. Recently, a role of the interleukin-23/T-helper 17 axis in PRP has been described. Our objective was to assess the effectiveness of ustekinumab in five patients with adult-onset PRP refractory to conventional therapies. In the present study, four patients had type I and one patient type II adult-onset PRP. They were treated with three s.c. doses of ustekinumab at weeks 0, 4 and 16. Clinical response was evaluated monthly during treatment up to a 15-month follow-up period. All patients promptly showed a decrease in erythema, follicular hyperkeratosis and scaling. After three injections, complete remission of skin lesions was achieved in four out of five cases and a significant clinical improvement was shown in one case. To the best of our knowledge, this is the largest case series reported on ustekinumab treatment in PRP. Our results, in addition to previous studies from other groups, suggest that ustekinumab may be a possible first-line treatment for PRP patients refractory to conventional therapies.