Idiopathic giant-cell granulomatous hypophysitis. Report of a case with autopsy follow-up.

Idiopathic granulomatous inflammation of the pituitary gland occurs rarely, and is usually identified as an incidental finding at autopsy. However, it may present during life as a mass lesion that clinically mimics other more common pituitary gland lesions. We report a 54-year-old woman presenting with acute onset diabetes insipidus whose MRI showed a 1.1 cm pituitary mass, with infundibular thickening and meningeal enhancement. Biopsy demonstrated granulomatous hypophysitis with multinucleate histiocytes. Special studies for infectious organisms were negative. The patient's disease progressed following biopsy, causing complete loss of vision in the right eye. This responded to high-dose steroids and local lowdose radiation. She later developed an acute inferior myocardial infarction. Laboratory tests failed to demonstrate an underlying autoimmune process. While recovering from this myocardial infarction, she succumbed to pulmonary embolism. Autopsy revealed moderate residual chronic infundibular inflammation. No evidence of systemic or residual pituitary granulomatous disease was identified. To the best of our knowledge, this is the first case of idiopathic granulomatous hypophysitis initially diagnosed by biopsy to have post-mortem neuropathologic examination.