Pituitary Tumors Composed of Adenohypophysial Adenoma and Rathke's Cleft Cyst Elements

ABSTRACT

Rathke's cleft cysts are believed to be derived from remnants of Rathke's pouch, a dorsal invagination of the stomodeum. Although these cysts are characteristically small, asymptomatic and intrasellar in location, they occasionally provoke symtoms with enlargement to compress surrounding structures. It is characteristically lined by stratified squamous epithelium with keratinization on a layer of connective tissue. The cells of the anterior pituitary lobe, from which pituitary adenomas develop, are also formed by the proliferation of the anterior wall of Rathke's pouch. Thus, Rathke's cleft cyst and pituitary adenomas are considered to have a common ancestry. We report a rare case in which the preoperative diagnosis was pituitary adenoma, but the pathologic diagnosis was a combination of a Rathke's cleft cyst and a coincidental pituitary adenoma.