Isolated Langerhans cell histiocytosis of the infundibulum presenting with fulminant diabetes insipidus

Introduction: Langerhans cell histiocytosis (histiocytosis X) is a rare disorder that can manifest with solitary bony lesions or disseminated disease in various tissues. A common manifestation of the disease is diabetes insipidus even in the absence of neural involvement. Disseminated disease often involves the central nervous system, but only six isolated lesions in the infundibulum have been reported. Case report: An 18-year-old male had failed to develop secondary sexual characteristics. He also had diabetes insipidus for more than 1 year. Magnetic resonance imaging (MRI) of the brain showed a 1-cm homogeneously enhancing mass in the region of the infundibulum. No other lesions were found in other organ systems. The patient underwent an orbitozygomatic osteotomy and pterional craniotomy. The lesion, which was adherent to the infundibulum, was partially resected. Microscopic analysis showed multiple lymphocytes and eosinophils with Langerhans cells that stained positive for S-100. Langerhans cell histiocytosis was diagnosed, and the patient was discharged on postoperative day 6 with no neurological deficits. His diabetes insipidus persisted, and he underwent intensity-modulated radiation therapy to the sellar region. Conclusions: Isolated Langerhans cell histiocytosis of the infundibulum is rare. The usual presentation is hypothalamic-pituitary axis dysfunction and diabetes insipidus. Patients with diabetes insipidus of unknown origin should undergo MRI of the sellar region to rule out infundibular abnormalities.