As per the recent cases, the reports have shown the efficacy of apremilast for treating palmoplantar pustulosis (PPP). However, no study has statistically analyzed the clinical efficacy of oral apremilast in patients with PPP. The study’s objective was to evaluate the effectiveness of apremilast, a phosphodiesterase four inhibitor, for PPP. Among 13 patients diagnosed with PPP, ten patients with PPP with either palmoplantar pustules (>1 mm diameter) or sternoclavicular joint pain were retrospectively analyzed.

Palmoplantar Pustulosis Area and Severity Index and the number of pustules measuring > 1 mm in diameter significantly improved in 2 weeks. Moreover, the Dermatology Life Quality Index and palmoplantar itching significantly improved in 2 weeks, whereas VAS scores of palmoplantar pain and sternoclavicular joint pain did not improve substantially. Diarrhea was observed in 60.0% of our patients. Our study demonstrated that apremilast could effectively treat cutaneous manifestations and arthralgia in Japanese patients with PPP who had apparent pustules and clavicular‐sternocostal arthralgia. That resulted from the retrospective design of the study and the small sample size. Placebo-controlled clinical trials with a larger number of patients are warranted to confirm the efficacy of apremilast for PPP treatment.