Predictors of residual and recurrent pituitary neuroendocrine tumors: impact of medial cavernous sinus wall invasion and Trouillas grading

Purpose: To identify the histopathological and radiological variables that can predict tumor persistence and recurrence at follow-up in Pituitary neuroendocrine tumors (PitNets) classified by Trouillas’ grading system. Methods: A total of 187 PitNets with medium (Knosp grades 2 and 3 A) and high risk (Knosp grades 3B and 4) for medial wall of the cavernous sinus (MWCS) invasiveness were classified according to the Trouillas’ score. The predictive value of Trouillas’ final grading system, along with radiological (lobulated configuration, tumor volume, T2 signal intensity values) and surgical/histopathological variables (invasiveness, proliferative status) was evaluated for forecasting tumor persistence and recurrence. Results: Discrepancies between surgical MWCS invasiveness and Knosp grades 2, 3 A, and 3B emerged within Trouillas grades 2a and 2b. Post-surgery, residual tumors were found in 91 out of 187 cases, predominantly near cavernous sinuses and in Trouillas grades 1b, 2a, and 2b. During follow-up, 40 cases had stable residue, while 52 cases exhibited recurrence, more frequently in Trouillas grades 2a and 2b. Residual and recurrent tumor prediction emerged by separating the Trouillas grades into invasive and non-invasive. MWCS invasiveness (p = 0.031), lobulated tumor configuration (p = 0.044), and low nT2min values (< 0.001) were the primary predictors of residual tumor; whereas only MWCS invasiveness (p = 0.008) predicted tumor recurrence. Conclusion: In PitNets, MWCS invasiveness remains the foremost independent prognostic factor for both residual tumor and recurrence.