Immediate response to apremilast in patients with palmoplantar pustulosis: a retrospective pilot study

BACKGROUND: Recent case reports have shown the efficacy of apremilast for the treatment of palmoplantar pustulosis (PPP). However, no study has statistically analyzed the clinical efficacy of oral apremilast in patients with PPP. OBJECTIVES: To evaluate the effectiveness of apremilast, a phosphodiesterase 4 inhibitor, for PPP. MATERIALS AND METHODS: Among 13 patients who were diagnosed with PPP, 10 patients with PPP with either palmoplantar pustules (>1 mm diameter) or sternoclavicular joint pain were retrospectively analyzed. RESULTS: Palmoplantar Pustulosis Area and Severity Index (mean ± SD: baseline, 13.4 ± 9.5 vs. after treatment, 5.1 ± 5.6; P = 0.013) and the number of pustules measuring > 1 mm in diameter (3.9 ± 3.9 vs. 1.3 ± 1.9; P = 0.029) significantly improved in 2 (±1) weeks. Moreover, the Dermatology Life Quality Index (9.7 ± 7.0 vs. 3.3 ± 3.6; P = 0.009) and palmoplantar itching (visual analog scale [VAS] score) (5.6 ± 3.5 vs. 2.1 ± 2.2; P = 0.026) significantly improved in 2 weeks, whereas VAS scores of palmoplantar pain (4.8 ± 4.4 vs. 1.1 ± 2.4; P = 0.081) and sternoclavicular joint pain (3.2 ± 3.8 vs. 2.0 ± 2.6; P = 0.194) did not significantly improve. Diarrhea was observed in 60.0% of our patients. CONCLUSION: Our study demonstrated that apremilast can effectively treat cutaneous manifestations and arthralgia in Japanese patients with PPP who had apparent pustules and/or clavicular‐sternocostal arthralgia. Owing to the retrospective design of the study and a small sample size, placebo‐controlled clinical trials with a larger number of patients are warranted to confirm the efficacy of apremilast for treatment of PPP.