Adult Langerhans cell histiocytosis of the central nervous system.

Langerhans cell histiocytosis (LCH), a disorder characterized by aberrant function and proliferation of mononuclear phagocytic cells called Langerhans cells, usually occurs in those <15 years of age. Adult-onset LCH is extremely rare. We present a case of a 35-year-old woman who presented with multiple episodes of confusion, rapidly progressive cognitive decline, and multiple endocrinopathies, including diabetes insipidus. Brain imaging showed a hypothalamic lesion, and biopsy results confirmed the diagnosis of LCH. Given the wide variety of presentations and the multiple differential diagnoses of hypothalamic lesions, it is essential to be aware of this uncommon condition, especially in adults, where it may be underdiagnosed.