Panhypopituitarism in Neurosarcoidosis: Pituitary-Hypothalamic Involvement Successfully Managed With Rituximab.

Neurosarcoidosis (NS) is a rare form of sarcoidosis, with isolated hypothalamic-pituitary involvement being exceptionally uncommon. We report a 20-year-old woman presenting with polyuria, galactorrhea, amenorrhea, and substantial weight loss. Hormonal evaluation revealed hypopituitarism with arginine-vasopressin deficiency and hyperprolactinemia. Magnetic resonance imaging demonstrated pituitary stalk thickening and suprasellar extension, initially suggestive of hypophysitis. High-dose glucocorticoid therapy resulted in partial regression of the pituitary lesion but persistence of suprasellar involvement, prompting a transcranial stereotactic biopsy. Histopathological analysis confirmed isolated NS with noncaseating granulomas. The patient was treated with rituximab after partial response to glucocorticoids, achieving significant clinical and radiological improvement, although hormonal axis recovery was not observed. Hormone replacement therapy remains necessary. The case met the criteria for definitive type b NS, as no extraneural involvement was identified. This case underscores the diagnostic challenges of isolated NS and highlights the importance of considering histopathological confirmation in patients without systemic manifestations to guide treatment. Glucocorticoids are first-line therapy, but rituximab may be effective as a second-line option for refractory cases. Early diagnosis and tailored therapy are essential to improving outcomes in this rare and challenging condition.