Xanthomatous Hypophysitis: A Novel Entity of Obscure Etiology

We report a case of xanthomatous hypophysitis, a recently described entity of obscure etiology affecting the pituitary gland, in a 43-yr-old woman, Histologically it is characterized by infiltration of the anterior pituitary by foamy histiocytes which are strongly immunoreactive for CD68 (histiocytic marker) and are immunonegative for 5100 and CD 1 a. Electron microscopy revealed histiocytes with abundant cytopasmic lipid droplets and membrane bound vacuoles. Fragments of intact anterior pituitary with preserved vascw lar and reticulin networks are seen. Xanthomatous hypophysitis resembles neoplasm on clinical and radiologic grounds.