P11.40.A Clinicopathological Analysis of High risk Pituitary Adenomas According to the 2017 WHO Classification System for Pituitary Neuroendocrine Tumors (PitNET)

Abstract

Abstract Background The 2017 WHO classification of pituitary tumors has revealed “high-risk pituitary neuroendocrine tumors (PitNETs)”, which were known to have high probability for recurrence. Tumor invasion was not included in the pathological grading and classification due to frequent lack of proper pathologic assessment. However, it mentioned tumor invasion as an important prognostic feature in identifying clinically aggressive adenomas. Material and Methods We performed a retrospective review of a prospectively collected dataset from January 2018 to March 2021. Patient’s clinical presentation, radiologic features, pathologic findings, and clinical outcome were gathered. Inter-group analysis was performed for high-risk versus low-risk tumors, and invasive versus non-invasive tumors. Results Among total 116 cases of PitNETs, high-risk and low-risk tumors were identified in 32 and 84 cases, respectively. The inter-group comparison showed no differences in clinical presentation, radiologic features, pathologic findings, and clinical outcomes.Invasive and non-invasive tumors were identified in 49 and 67 cases, respectively. The invasive group tumors were more symptomatic ( 29 (59.2%) vs. 30 (44.8%), p= 0.031), with larger tumor size over 40mm (9 (18.4%) vs. 1 (1.5%), p = 0.002), and more likely to have Knosp grade higher than 3. The gross-total resection was less achievable (7 (14.3%) vs 26 (38.8%), p = 0.007) However, Ki-67 index showed no significantly difference between the invasive group and non-invasive group (2.0 vs 2.0 , p= 0.556). Conclusion According to our study results, the pathologic diagnosis of a high-risk tumor does not necessarily seem to properly reflect the clinical aggressiveness. Tumor invasion, however, seems to better represent the aggressive tumors that requires proper and active treatment.