Neurosarcoidosis-Induced Hypophysitis Mimicking Pituitary Macroadenoma

Sarcoidosis is characterized by the presence of noncaseating granulomatous inflammation in the affected organs. Isolated involvement of the hypothalamic-pituitary axis in patients with sarcoidosis is rare. We report a rare case of a female patient in whom hypophysitis, mimicking a pituitary macroadenoma, resulted in pituitary transsphenoidal surgery. A female patient had been complaining of bilateral temporal headaches for over a month. Brain MRI showed a pituitary adenoma of height 16 mm, width 16 mm, and depth 12 mm. Hormonal assay showed central hypothyroidism and elevated level of prolactin. Histological examination revealed granulomatous hypophysitis. A specific search for Mycobacterium tuberculosis was negative on the pituitary tissue. After the exclusion of differential diagnoses, the combination of clinical, laboratory and radiological tests led to the diagnosis of neurosarcoidosis. This report presents an uncommon case of a pituitary localization of neurosarcoidosis mimicking a macroadenoma. Understanding the different MRI aspects of neurosarcoidosis is essential to avoid interpretive blunders that could result in an incorrect diagnosis.