An Unusual Presentation of Multisystem Langerhans Cell Histiocytosis in a Child: A Case Report.

Langerhans cell histiocytosis (LCH) is a rare clonal myeloid disorder with a broad clinical spectrum ranging from isolated lesions to multisystem disease. We report the case of a two-year-five-month-old boy who presented with a six-month history of treatment-refractory bilateral otorrhea, progressive mandibular swelling with premature tooth loss, seborrheic skin lesions, and weight loss. Further evaluation revealed severe polyuria-polydipsia suggestive of central diabetes insipidus. Imaging demonstrated multifocal craniofacial osteolytic lesions with hypothalamic-pituitary involvement. Histopathological examination of a mandibular biopsy, supported by positive CD1a, S100, and CD68 immunostaining, confirmed the diagnosis of LCH. The patient was classified as having multisystem LCH without risk-organ involvement and was treated according to the LCH-III protocol with vinblastine and prednisone, alongside desmopressin therapy. At one-year follow-up, he showed significant clinical and radiological improvement without evidence of disease progression. This case highlights the diagnostic challenges of multisystem LCH in young children and emphasizes the importance of considering LCH in patients presenting with persistent otologic symptoms, craniofacial bone lesions, premature tooth loss, and diabetes insipidus.