Diabetes insipidus associated with a thickened pituitary stalk in a case of Langerhans Cell Histiocytosis.

Diabetes insipidus (DI) associated with a thickened pituitary stalk is a diagnostic challenge in the pediatric population. Langerhans Cell Histiocytosis (LCH) is a rare cause of this entity. A 4-year-old male child presented with central DI of 1-year duration, associated with a thickened pituitary stalk. The etiology for the same remained elusive as the patient had no other manifestation to suggest LCH. A year later, the patient developed a left frontal scalp swelling. Neuroradiology demonstrated multiple punched out osteolytic lesions in both the frontal bones. The infundibulum was thickened and showed post-contrast enhancement. Histology and immunohistochemistry (IHC) of the biopsy specimen confirmed LCH. The child was administered chemotherapy according to LCH protocol, which resulted in 33% reduction in the size of the skull lesions. The DI was controlled with medical management. The present case highlights the need for serial follow-up and magnetic resonance (MR) imaging that led to a diagnosis of LCH. The clinical presentation and management of central DI and a thickened pituitary stalk is presented and the relevant literature is discussed.