Abstract
Palmoplantar pustulosis (PPP) is a chronic, relapsing disease with sterile pustules involving the palms and soles. The pathogenesis of PPP remains unclear and there is currently no standard treatment. We present three cases of recalcitrant PPP treated with topical 2% crisaborole cream in our clinic from October 2024 to February 2025. All of the patients had received skin biopsy to prove their diagnosis and had been treated with various treatments with limited response. After 4 weeks of topical crisaborole, their palmoplantar pustulosis area and severity index decreased from 7.2 to 2.8, 9 to 1.8, and 28.4 to 0, respectively. Given that PPP involves the skin locally, an effective topical treatment may provide a convenient, inexpensive alternative for such patients. The positive response of topical crisaborole observed in our cases also echoes the efficacy of apremilast, a systemic phosphodiesterase 4 (PDE4) inhibitor which successfully treated PPP in other reports, highlighting the potential role of PDE4 in the pathophysiology of PPP. Further studies are needed for a more comprehensive evaluation.