A Rare Case of Adipsic Diabetes Insipidus Associated with Langerhans Cell Histiocytosis

ABSTRACT Objective: We describe a case of adipsic diabetes insipidus, hypopituitarism, and cognitive impairment in a patient with a hypothalamic mass diagnosed with Langerhans cell histiocytosis. We aim to highlight the difficult and complex management of such a rare case. Methods: We report the initial presentation, laboratory results, imaging, management, complications, and outcome of a patient with adipsic diabetes insipidus. We conducted a literature search to review the reported cases of adipsic diabetes insipidus. Results: A previously well 36-year-old woman presented with amenorrhea, headaches, polyuria, polydipsia, and cognitive decline. Initial investigations demonstrated serum hypernatremia (156 mmol/L), hyperosmolality (322 mmol/kg), and inappropriate hypotonic polyuria (urine osmolality 100 mmol/kg, urine output 500 mL/hour). Pituitary investigations showed hyperprolactinemia and secondary hypothyroidism, hypocortisolemia, and hypogonadism. Magnetic resonance imaging brain scan revealed a 1.6 × 2.3 × 1.9 cm enhancing hypothalamic mass. She displayed an appropriate renal response to desmopressin (urine osmolality 400 to 500 mmol/kg, urine output <100 mL/hour) and thus was diagnosed with central diabetes insipidus. Histopathology from partial tumor resection confirmed Langerhans cell histiocytosis. During her course, she developed adipsia and worsening cognitive impairment, resulting in chronic hypernatremia (average sodium 152 mmol/L reaching up to 180 mmol/L) due to poor compliance with desmopressin, strict fluid balance, and prescribed fluid intake. She died at 9 months after initial presentation without ever completing her chemoradiotherapy. Conclusion: Adipsic diabetes insipidus is a rare and dangerous condition and especially difficult to manage when combined with cognitive dysfunction. We urge clinicians to consider the diagnosis of Langerhans cell histiocytosis in patients presenting with a hypothalamic mass, diabetes insipidus, hypopituitarism, and cognitive impairment. Abbreviations: ADH = antidiuretic hormone;DI = diabetes insipidus;IV = intravenous;LCH = Langerhans cell histiocytosis