Intratumoral granulomatous reaction in recurrent pituitary adenoma: A unique presentation

Pituitary adenoma is one of the most common intracranial neoplasms, usually presenting with endocrinopathies or visual field defects. Granulomatous hypophysitis, one of the subtypes of primary hypophysitis, is a rare neurological entity presenting as a sellar lesion with mass effect symptoms and endocrinological dysfunction. Majority of cases of primary hypophysitis are misdiagnosed as pituitary adenomas preoperatively, and histopathology is required for a definitive diagnosis. Granulomatous hypophysitis can be primary/idiopathic or secondary to a variety of causes such as infection, foreign body reactions, and systemic inflammatory conditions. The presence of tumoral microgranulomas in pituitary adenoma is exceedingly rare, having been documented only twice previously. We present a unique case of recurrent pituitary macroadenoma in a 59-year-old woman with histopathological features of idiopathic intratumoral noncaseating granulomatous inflammation. The presence of a granulomatous response in the absence of a systemic infectious or inflammatory disorder is suggestive of a local tumoral response to an as-yet unidentified antigen.