2025 Proffered Presentations
S005: IDENTIFICATION OF PITUITARY ADENOMAS WITH SUBARACHNOID INVASION: INTRODUCTION AND VALIDATION OF THE NET SCORE
Jonathan B Lamano, MD, PhD1; Christine K Lee, MD, PhD2; Ana Sofia Alvarez, MD1; Karam P Asmaro, MD3; Enrico Gambatesa, MD1; Felipe Constanzo, MD1; Adrian J Rodrigues, MD1; Juan Carlos Fernandez-Miranda, MD1; 1Stanford University; 2Brown University; 3Henry Ford Health
Introduction: Pituitary adenomas with subarachnoid invasion represent a challenging subset of tumors characterized by invasion through the arachnoid plane and encasement of critical neurovascular structures. Unlike adenomas that respect the arachnoid plane, adenomas with subarachnoid extension are associated with worse clinical outcomes and require a modified surgical approach involving an expanded exposure and careful extracapsular dissection to avoid injury to surrounding neurovascular structures. Pre-operative identification of these lesions is necessary for appropriate surgical planning and patient counselling.
Methods: Data from 333 pituitary adenomas treated from 2018-2023 were analyzed. MRI studies were evaluated to identify predictors of subarachnoid tumor invasion. Subarachnoid invasion was confirmed intraoperatively during intervention with an endoscopic endonasal, open transcranial, or combined endoscopic and open approach. Univariate and multivariate analyses were performed to identify factors associated with subarachnoid invasion and a predictive score was developed. Data from 102 pituitary adenomas treated from 2023-2024 were used to validate the predictive score.
Results: Subarachnoid invasion was present in 7% of patients (22/333) who underwent pituitary adenoma resection. Tumors with subarachnoid invasion were larger than tumors without subarachnoid invasion (27mm versus 19mm, p<0.01). In addition, dumbbell tumor morphology was more predominant (45% versus 12%, p<0.0001) and pituitary morphology more likely to be non-identifiable in patients with subarachnoid invasion (36% versus 11%, p<0.001). Nodular tumor extension was a characteristic feature of adenomas with subarachnoid invasion (91% versus 9%, p<0.00001), with a high degree of multinodularity present (59% versus 3%, p<0.00001). Vascular involvement represented another distinctive feature of subarachnoid invasion, with increased subarachnoid vessel (59% versus 1%, p<0.00001) and cavernous carotid artery (32% versus 4%, p<0.00001) encasement. Overall, adenomas with subarachnoid invasion were predominantly Knosp grade 4 (32% versus 4%, p<0.00001) and more often T2 isointense (91% versus 60%, p<0.01). A multivariate analysis was performed which identified nodular extension (OR 109.1, p<0.001), subarachnoid vessel encasement (OR 103.2, p<0.001), and tumor diameter (OR 0.92, p<0.05) as significant predictors of subarachnoid invasion. A predictive score (NET score) based on the presence of nodular extension (2 points), subarachnoid vessel encasement (2 points), and tumor diameter greater than 20mm (1 point) was subsequently developed, with a NET score of 3 or greater associated with a sensitivity of 82% and specificity of 92% for detection of subarachnoid invasion (AUC=0.962). Utilizing a validation cohort of 102 patients, the NET score was validated with a sensitivity of 86% and specificity of 93% (AUC=0.974). Increasing NET scores were associated with increased utilization of open transcranial and combined endoscopic and open approaches, in addition to decreased gross total resection (p<0.05), increased need for additional treatment, and increased surgical complications.
Conclusion: Pituitary adenomas with subarachnoid invasion are associated with worse clinical outcomes and higher risk of iatrogenic injury compared to adenomas without subarachnoid extension. Pre-operative identification facilitates proper surgical planning including the consideration of combined endoscopic and open approaches. Based on the presence of nodular tumor extension, subarachnoid vessel encasement, and increased tumor diameter, the NET score can assist in the identification of subarachnoid invasion and guide intervention for these challenging tumors.
