Endoscopic distinction between capsule and pseudocapsule of pituitary adenomas

Pseudocapsules were first identified in pituitary adenoma surgery in 1936. Since then, the distinction between pituitary capsules and pseudocapsules has been unclear, and the definitions of these entities have varied. In this study, pituitary capsules and extracapsular dissection were examined retrospectively, intra- and extrapseudocapsular resection was evaluated, and dissection of the pituitary adenoma and pseudocapsule was examined prospectively.

Between January 2009 and May 2012, endoscopic transsphenoidal pituitary surgery was performed on 224 patients in the Department of Neurosurgery, Kocaeli University Faculty of Medicine, Turkey. Data for 174 patients were analyzed retrospectively between January 2009 and December 2011, and 50 patients treated between December 2011 and May 2012 were included in a prospective study.

In the retrospective phase of the study, capsules were examined in 21 of the 174 patients on whom extracapsular resection had been performed. In the 50 cases treated between December 2011 and May 2012, dissection of the pituitary capsule, adenohypophysis, and pseudocapsule was performed. In 30 patients in the prospective phase of the study, pseudocapsules were identified during intraoperative endoscopic observation. Remission was achieved in 28 of 33 functioning adenomas in the prospective study. The mean follow-up period in this group was 13 months.

The endoscopic and histopathological evidence provided in this study demonstrates that the pituitary capsule and pseudocapsule are distinct structures. In addition, it is also shown that extracapsular dissection can be performed in functioning adenomas that invade the suprasellar region. Significantly higher rates of total resection and higher remission rates were observed in cases where extra- and intrapseudocapsular dissection was required.