SUN-032 Central Diabetes Insipidus and Spontaneous Pneumothorax in Langerhans Cell Histiocytosis: A Case Report

Abstract Disclosure: M. Lopez Baez: None. I. Abarca: None. G. White: None. C. Sanchez Perez: None. S. Gra Menendez: None. Langerhans Cell Histiocytosis (LCH) is a rare systemic disorder characterized by clonal proliferation of Langerhans cells, with potential involvement of multiple organs, including the lungs and hypothalamic-pituitary axis. We present the case of a 29-year-old male with a history of spontaneous pneumothorax and a new diagnosis of LCH, complicated by transient central diabetes insipidus (DI).The patient initially presented with recurrent pneumothorax requiring thoracic intervention. He subsequently developed persistent polyuria and polydipsia, raising concern for an endocrine etiology. Brain MRI revealed scattered non-enhancing T2 hyperintense foci within the posterior fossa, partially empty sella, and absent T1 hyperintensity of the posterior pituitary gland, consistent with central DI secondary to LCH. A right lower lobe lung wedge resection confirmed small clusters of CD1a- and S100-positive cells, supporting the diagnosis of LCH. Laboratory findings showed hypernatremia, low urine osmolality, and symptomatic relief with desmopressin, confirming central DI. Surprisingly, at follow-up, the patient no longer required desmopressin therapy, suggesting potential resolution or stabilization of pituitary dysfunction. This case highlights the diagnostic complexity of LCH with multi-organ involvement and the importance of recognizing polyuria and polydipsia as red flags for central DI. A multidisciplinary approach integrating endocrinology, thoracic surgery, and radiology was critical in diagnosing and managing this multisystemic disease. Tailored interventions, including pleurodesis and transient desmopressin therapy, improved the patient’s clinical stability. The variability of endocrine dysfunction in LCH underscores the need for close monitoring and follow-up to optimize outcomes. Presentation: Sunday, July 13, 2025