Nail Langerhans Cell Histiocytosis: A Rare Case Series of Two Patients With Single-System and Multisystem Disease Presenting With Nail Lesions

ABSTRACT: Langerhans cell histiocytosis (LCH) is a rare myeloid neoplastic disorder driven by somatic MAPK pathway mutations, most commonly BRAFV600E, characterized by clonal proliferation of CD1a+/CD207+ dendritic cells forming granulomatous lesions in various tissues. Nail involvement is an uncommon but clinically significant manifestation, often associated with multisystem disease and a potentially poorer prognosis. We report 2 pediatric cases of LCH presenting with nail changes as the initial clinical feature. Case 1, a 2-year-old boy, was presented with longitudinal grooving, onycholysis, subungual hyperkeratosis, and purpuric striae of nearly all fingernails. Staging investigations revealed only mild lymphadenopathy, and BRAF mutation testing was negative. He was treated with methylprednisolone and vinblastine, achieving metabolic inactivity at 9 months. Case 2, a 19-month-old boy, was presented with diffuse fingernail and toenail dystrophy followed by cutaneous papules and was found to have multisystem disease involving bone and lungs. Nail bed, skin, and bone biopsies confirmed LCH. Systemic chemotherapy with vinblastine and prednisone led to marked improvement in nail, skin, pulmonary, and osseous lesions. These cases illustrate that nail changes may be the earliest manifestation of LCH and should prompt thorough systemic evaluation. Early recognition of nail involvement can facilitate timely diagnosis and risk-adapted treatment, potentially improving outcomes in affected patients.