Large Pituitary Adenoma: Strategies to Maximize Volumetric Resection Using Endoscopic Endonasal Approaches and an Analysis of Factors Limiting Resection

Large pituitary adenomas (LPAs), which constitute ∼5%-14% of all pituitary adenomas, are considered challenging tumors owing to their locally aggressive behavior, low gross total resection rate, and high prevalence of visual deficits and hypopituitarism. We evaluated the utility of various extended endoscopic endonasal approaches in maximizing the resection of LPAs and studied the factors affecting the extent of surgical resection.A retrospective study of all LPAs (defined as a minimum diameter >3 cm and tumor volume >10 cm3) treated via an endoscopic endonasal approach between January 2015 and December 2020 was performed. The volumetric extent of resection (3-dimensional volumetric analysis software) was correlated with various demographic, tumor-related, pathologic, and immunohistochemical factors and its effects on the clinical outcomes studied.The present study included 106 patients with LPAs. The mean extent of the resection volume was 79.18 ± 21.75 cm3. The factors that affected the extent of resection included the preoperative tumor volume (P = 0.03) and Knosp grade (P = 0.03). The percentage increase in the extent of resection with the use of 2 endonasal corridors was 10.6% and with 3 corridors was 14%. Visual improvement occurred in 82% of patients, and new-onset persistent hormonal insufficiency occurred in 2.9% of patients. Mortality directly related to surgery occurred in 1.8% of cases.Extended endoscopic endonasal approaches can safely and effectively be used for gross total resection of LPAs. However, we found that the preoperative tumor volume and Knosp grade were significant factors affecting the extent of tumor resection. The use of multiple endoscopic endonasal corridors can increase the volumetric extent of resection for LPAs.