Sources of residuals after endoscopic transsphenoidal surgery for large and giant pituitary adenomas.

Large and giant PAs are challenging lesions with high subtotal resection rates. Suprasellar AP distance, retrosellar extension, and higher Zurich Score seem to be significant predictors of degree of resection in these tumors. Improving the intraoperative ability to distinguish tumor from a normal tissue might further decrease the number of unexpected residuals.