Refractory Adult-Onset Localized Cutaneous Langerhans Cell Histiocytosis Successfully Treated with Surgical Intervention: Case Report.

Langerhans cell histiocytosis (LCH) is a rare clonal proliferative disorder that frequently mimics common inflammatory dermatoses, often resulting in delayed diagnosis. We report a highly deceptive clinical presentation. A 36-year-old man presented with a five-year history of painful, refractory ulcerated plaques on his bilateral groins. Previous empirical therapies failed completely. A targeted skin biopsy eventually revealed classic atypical Langerhans cells with reniform nuclei, demonstrating striking immunohistochemical positivity for CD1a and CD207. Comprehensive systemic investigations confirmed isolated cutaneous involvement. Although subsequent trials of systemic agents-including thalidomide, methotrexate, and upadacitinib-were poorly tolerated and offered limited benefit, surgical excision ultimately achieved complete resolution. The patient has not presented recurrence at 18-month follow-up. This case highlights the critical necessity of an early biopsy for chronic intertriginous ulcers. Furthermore, it demonstrates that surgical management serves as a safe and durable definitive strategy for recalcitrant, localized cutaneous LCH.