Improvement of Nail Dystrophy Secondary to Atopic Dermatitis With Low-Frequency Dupilumab Dosing: A Case Report

A 50-year-old male with a longstanding history of atopic dermatitis (AD) presented with chronic nail dystrophy of 15 years' duration. He reported lifelong nail clubbing but denied pulmonary disease or environmental triggers such as frequent handwashing. Examination revealed multifocal dystrophic, onycholytic, and erosive nail changes with punctate depressions, jagged borders, nail matrix fragmentation, and reduced translucency. Additional findings included xerosis, fissuring of the hands, and pink scaly plaques on the dorsal hands and foot. Differential diagnoses included median canal dystrophy, habit tic deformity, and irritant contact dermatitis. Fungal culture grew Candida parapsilosis, and patch testing revealed allergies to methyldibromoglutaronitrile (MDBGN), cocamidopropyl betaine, dimethylaminopropylamine (DMAPA), and oxybenzone. Despite trials of topical econazole, clobetasol, oral terbinafine, and methotrexate, the patient experienced no improvement and was lost to follow-up. Two years later, he re-presented with worsening fissuring and dryness. Dupilumab was initiated with a loading dose of 600 mg followed by 300 mg every 14 days. After five months and four doses, the patient exhibited marked improvement in nail and cuticle appearance, with near-complete resolution of fissuring and peeling. Dupilumab was then tapered to 300 mg every 21 days. At follow-up, mild cuticular erythema and xerosis recurred, but overall nail improvement was maintained. This case highlights a unique presentation of chronic nail dystrophy associated with atopic dermatitis and multiple contact allergies, refractory to standard therapies but responsive to dupilumab. Dupilumab may be an effective treatment for chronic nail involvement in AD, even when traditional topical, systemic, and antifungal therapies fail.