Amicrobial Pustulosis of the Folds Successfully Treated With Apremilast: Report of Two Cases and Review of the Literature

Amicrobial pustulosis of the folds (APF) is a rare, chronic-relapsing neutrophilic dermatosis characterized by sterile pustules affecting major and minor skin folds. It predominantly affects women and is frequently associated with autoimmune diseases such as systemic lupus erythematosus, inflammatory bowel disease, and autoimmune thyroiditis. Due to its rarity, standardized treatment guidelines are lacking, and management remains challenging. Systemic corticosteroids, dapsone, colchicine, methotrexate, and biologics have been employed with variable outcomes, but long-term control is often difficult to achieve. Apremilast, an oral phosphodiesterase-4 inhibitor with anti-inflammatory properties, has demonstrated efficacy in various neutrophilic dermatoses. We report two women with treatment-refractory APF who achieved clinical remission within 2 months of initiating apremilast, with sustained disease control at 6 months and successful corticosteroid tapering. A literature review of 78 APF cases confirmed a strong female predominance (93.6%) and frequent association with autoimmune conditions (91%). Systemic corticosteroids were the most frequently employed treatment but often failed to provide sustained disease control without the addition of other systemic agents. These cases represent the first reports of apremilast use in APF and suggest its potential as a safe and effective steroid-sparing option in patients with refractory disease. Further studies are needed to validate its role in this setting.