XANTHOMATOUS HYPOPHYSITIS

Inflammatory lesions of the hypophysis include lymphocytic hypophysiti s, pituitary abscess, and granulomatous inflammation, with or without specific infections (i.e., sarcoidosis, mycobacteria). These lesions a re known to mimic pituitary neoplasms. We report the clinical and path ologic findings in three patients who underwent transsphenoidal resect ion for presumed pituitary adenoma. Two were women aged 30 years (one with a 5-month history of headache, the other with a I-year history of menstrual irregularity) and one was a 12-year-old girl with headache, nausea, and diabetes insipidus. Preoperative endocrinologic studies s howed increased prolactin in one patient and normal serum thyroid stim ulating hormone and prolactin levels in another. By magnetic resonance imaging (MRI), the first case had a 1.2-cm mass with increased signal on T1 and isointensity on T2, ring enhancement after gadolinium, and lateral deviation of the pituitary stalk. The second patient had a 1.1 -cm ''cystic'' mass seen during magnetic resonance imaging with adjace nt bony changes seen during computed tomography. In the third, compute d tomography showed a hypodense pituitary mass that enlarged during 1- month observation. At surgery, abnormal soft tissue surrounded liquefi ed material in the anterior pituitary in all cases. Histologic studies showed fragments of intact normal anterior pituitary with preserved v ascular and reticulin network and regions of anterior pituitary infilt rated by foamy histiocytes. Other fragments resembled granulation tiss ue, and some consisted of acellular debris. Histiocytes were immunorea ctive for the macrophage marker CD68 and negative for S-100 and CD1a. Ultrastructurally, the normal adenohypophysis was permeated by lipid-l aden macrophages. Then were no well-formed granulomas or giant cells, hemosiderin, acid-fast bacilli, or fungi. Serial sections and keratin immunostains failed to identify an epithelial cyst lining or keratin a mong the debris. We propose the term ''xanthomatous hypophysitis'' for this lesion.