Granulomatous hypophysitis caused by a ruptured intrasellar Rathke's cleft cyst: report of a case and review of the literature.

Abstract

Ruptured Rathke's cleft cyst is a rare cause of giant cell granulomatous hypophysitis. Chronic inflammatory reaction is caused by extravased cyst content into the adjacent gland. We provide a demonstration that mucins produced by cells lining the cyst wall caused the granulomatous giant cell reaction. A 37-year-old nonpregnant woman presented with a 3-year-history of headache and amenorrhea. She had experienced normal sexual maturation, and her medical history was unremarkable. Radiologically, the lesion appeared as an intrasellar mass with a cystic component indistinguishable from a pituitary adenoma with cystic degeneration. The patient underwent a transsphenoidal approach. Because no demarcation between normal and affected tissue was evident at surgery, the lesion and residual pituitary were radically removed. Tissue was studied using routine hematoxylin and eosin and histochemical stainings for mucins and immunocytochemical techniques. This study demonstrates that mucins that had spilled out from the cyst caused the granulomatous reaction. Using computed tomography, magnetic resonance imaging, and gross inspection, distinction between granulomatous hypophysitis and pituitary adenoma was virtually impossible. Nevertheless, a granulomatous reaction of the pituitary gland should be suspected in a case of a sellar mass having a cystic area. In such cases, intraoperatory diagnosis on frozen sections is mandatory because adoption of a conservative treatment allows preservation of the gland.