IMG-34. Postoperative resolution of brainstem leptomeningeal enhancement in glioblastoma: implications for diagnosis and management

BACKGROUND Leptomeningeal enhancement (LME) on magnetic resonance imaging is typically indicative of leptomeningeal dissemination (LMD) in glioblastoma, often correlating with poor prognosis. However, instances of LME resolution post-surgical resection suggest alternative etiologies. METHODS A retrospective analysis was conducted on 112 glioblastoma patients treated between 2017 and 2020. Among these, nine exhibited preoperative brainstem LME. Clinical and radiological data were reviewed, focusing on tumor characteristics and postoperative imaging outcomes. RESULTS Preoperative brainstem LME was observed in 8% (9/112) of patients. Larger tumor size was significantly associated with LME presence (p = 0.016), and a trend was noted for deeper tumor locations (p = 0.058). Of the six patients undergoing surgical resection, four demonstrated complete postoperative LME resolution. Among these, two patients showed sustained resolution with no recurrence during follow-up. Both of these tumors extended to the cortical surface and the ventricular wall. These patients exhibited survival times exceeding expectations for LMD cases. Notably, LME resolution was absent in patients receiving only biopsy or chemoradiotherapy. CONCLUSIONS The disappearance of LME following tumor resection suggests that such enhancements may not always signify true LMD. Alternative mechanisms, such as venous congestion from intratumoral arteriovenous shunting, may contribute to LME. Differentiating pseudo-LMD from true dissemination is essential for accurate diagnosis and optimized patient care.