title: Xanthomatous Hypophysitis Is Associated with Ruptured Rathke's Cleft Cyst.
abstract: Xanthomatous hypophysitis is a rare inflammatory disease of the pituitary gland that can mimic a neoplastic lesion clinically and radiologically. Its pathogenesis remains largely unknown, although recent evidence suggests that pituitary inflammation may occur as a secondary reaction to mucous content released from a ruptured cyst. In a series of 1221 pituitary specimens, we identified seven cases of xanthomatous hypophysitis. Six patients had complete radiological and biochemical workup preoperatively: a cystic-appearing pituitary mass was identified in all six patients (100%) with a mean size of 2.0 cm (range 1.4-2.5 cm) on imaging, and pituitary endocrine dysfunction was noted in five patients (83.3%). In all cases, the pituitary mass was resected through an endoscopic transsphenoidal approach. Pathological examination revealed the presence of foamy macrophages admixed with variable amounts of giant cells and chronic inflammatory cells, confirming the diagnosis of xanthomatous hypophysitis. Additionally, all cases presented with concurrent findings of ruptured Rathke's cleft cyst, with the exception of one patient who had previous surgery for a Rathke's cleft cyst, followed by recurrence and diagnosis of xanthomatous hypophysitis. While accurate distinction of hypophysitis from a pituitary neoplasm can be problematic in the preoperative setting, the identification of a cystic lesion in the sella turcica should raise the possibility of such an entity in the clinical and radiological differential diagnosis. The current series provides further evidence that xanthomatous hypophysitis predominantly occurs as a secondary reaction to a ruptured Rathke's cleft cyst; thus, it is best classified as a secondary (reactive) hypophysitis.
authors.affiliation: Department of Pathology, University Health Network, 200 Elizabeth Street, 11th floor, Toronto, ON, M5G 2C4, Canada.|Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
authors.forename: Kai
authors.initials: K
authors.lastname: Duan
authors.affiliation: Department of Pathology, University Health Network, 200 Elizabeth Street, 11th floor, Toronto, ON, M5G 2C4, Canada.|Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.|Endocrine Oncology Site Group, Princess Margaret Cancer Centre, Toronto, ON, Canada.
authors.forename: Sylvia L
authors.initials: SL
authors.lastname: Asa
authors.affiliation: Department of Pathology, University Health Network, 200 Elizabeth Street, 11th floor, Toronto, ON, M5G 2C4, Canada.|Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Winer
authors.affiliation: Endocrine Oncology Site Group, Princess Margaret Cancer Centre, Toronto, ON, Canada.|Department of Neurosurgery, University Health Network, Toronto, ON, Canada.
authors.forename: Zadeh
authors.initials: Z
authors.lastname: Gelareh
authors.affiliation: Endocrine Oncology Site Group, Princess Margaret Cancer Centre, Toronto, ON, Canada.|Department of Neurosurgery, University Health Network, Toronto, ON, Canada.
authors.forename: Fred
authors.initials: F
authors.lastname: Gentili
authors.affiliation: Department of Pathology, University Health Network, 200 Elizabeth Street, 11th floor, Toronto, ON, M5G 2C4, Canada. ozgur.mete2@uhn.ca.|Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada. ozgur.mete2@uhn.ca.|Endocrine Oncology Site Group, Princess Margaret Cancer Centre, Toronto, ON, Canada. ozgur.mete2@uhn.ca.
authors.forename: Ozgur
authors.initials: O
authors.lastname: Mete
mesh_terms: D000328:Adult; D020863:Central Nervous System Cysts / Q000150:complications* / Q000473:pathology*; D005260:Female; D006801:Humans; D000072659:Hypophysitis / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000150:complications* / Q000473:pathology*; D012189:Retrospective Studies; D012422:Rupture, Spontaneous; D014973:Xanthomatosis / Q000150:complications / Q000473:pathology
keywords: Hypophysitis; Pituitary adenoma; Rathke cleft cyst; Xanthomatous inflammation