Apremilast for Acrodermatitis Continua of Hallopeau: Report of Two Cases and Review of the Literature.

Acrodermatitis continua of Hallopeau (ACH) is a rare, localized variant of pustular psoriasis characterized by painful paronychia. It primarily affects the distal phalanges and is frequently refractory to standard topical treatments. Establishing an optimal systemic therapy is clinically challenging, particularly for women of childbearing age, given the teratogenicity of retinoids and methotrexate, as well as the adverse effect profiles associated with cyclosporine. Herein, we present two cases of Japanese women in their 30s with recalcitrant ACH who were treated with apremilast. In Case 1, erythema and pain resolved within two months. In Case 2, while skin lesions responded favorably, persistent joint symptoms and headaches necessitated a switch to risankizumab. To evaluate broader utility, we analyzed 10 ACH cases (our two and eight from literature). Clinical efficacy for skin lesions was observed in 90% (9/10), and the response rate for joint pain reached 80% (4/5), with a median response time of 2 months. Notably, apremilast also demonstrated a favorable safety profile even with comorbidities like viral hepatitis. Although 30% of patients experienced mild adverse events (e.g., nausea, headache), the medication was generally well-tolerated. While this review is limited by potential publication bias inherent to case reports, and treatment responses vary, with one study showing limited efficacy, apremilast may be considered among systemic treatment options. Given its non-teratogenic nature and cost-effectiveness compared to biologics, we recommend apremilast as one of the first-line systemic treatment options for ACH patients resistant to topical regimens, especially those of childbearing potential.