Multisystem multifocal langerhans cell histiocytosis in an adult presenting with classical triad: lytic bone lesions, exophthalmos, and diabetes insipidus - a rare case report

Langerhans Cell Histiocytosis (LCH) is a rare clonal disorder of antigen-presenting dendritic cells expressing CD1a, S-100, and Langerin (CD207). It may involve a single organ or multiple organ systems with variable severity. Adult-onset multisystem LCH is uncommon and easily misdiagnosed. We report a 28-year-old male presenting with the classical Hand-Schuller- Christian triad of osteolytic bone lesions, exophthalmos, and central diabetes insipidus . A skeletal survey and CT imaging revealed multifocal lytic lesions of skull, pelvis, and long bones with pulmonary and abdominal organ involvement. Histopathology confirmed LCH as CD1a+, S-100+ and Langerin(CD207) +. Management included systemic corticosteroids, vinblastine- based chemotherapy, and desmopressin, with counseling on smoking cessation and follow-up. This case underscores the need to recognize adult multisystem LCH to enable timely biopsy, risk stratification, and targeted therapy.