Objective In the present study we aim to provide further definition of a group of rare sellar diseases treated by the endoscopic endonasal approach. Methods The study was a retrospective analysis of data obtained from a series of 1729 patients who underwent endoscopic endonasal surgery at 2 academic institutions (Universita degli Studi di Napoli Federico II, Naples, Italy between January 1997 and December 2013 and the Wexner Medical Center at The Ohio State University between July 2010 and September 2015). Clinical charts, operative notes, and pathology reports were examined. Results A total of 346 cases were identified to have nonadenomatous diseases. Applying the Rosner test for outliers assisted in excluding relatively frequent lesions. The final cohort of rare sellar diseases comprised 78 patients. Arachnoid cysts were the most frequently encountered sellar lesion (12 patients, 15%), followed by metastasis (11 cases, 14%), followed by hypophysitis (8 cases, 10%), oncocytoma, and glioma (6 cases, 8% each). The most frequent clinical findings were headache (28%) and visual disorders (80%). A standard endoscopic endonasal approach was performed in 44 patients (56%), and an extended approach was carried out in 34 patients (44%). Tumor removal was gross total in 53% of patients, subtotal in 19%, and partial in 21%. Postoperative endocrinologic and visual deficit evaluation showed improvements in endocrine function in 8 patients (10%) and in visual disorders in 13 (16%). Postoperative complications arose in 28% of cases, mostly represented by diabetes insipidus (10%). Conclusions Endoscopic endonasal approaches offer some specific benefits in the treatment of these patients.
