BIOM-88. LEPTOMENINGEAL METASTASIS IN THE INTERNAL AUDITORY CANAL AS A PREDICTOR OF OUTCOMES FOR CHILDREN WITH CENTRAL NERVOUS SYSTEM TUMORS

Abstract BACKGROUND Metastatic disease is a significant factor in pediatric central nervous system (CNS) tumors that affects staging, treatment approach and overall prognosis. Enhancement of the internal auditory canal (IAC) is frequently observed, but little is published on how this relates to risk assessment. We hypothesized that among patients with leptomeningeal enhancement concerning for metastasis, IAC enhancement may predict poorer clinical prognosis. Here, we compare outcomes for patients with and without IAC enhancement and report specific imaging characteristics associated with these outcomes. METHODS We performed a retrospective analysis of pediatric patients treated at Cincinnati Children’s Hospital Medical Center from 2007-2024 for primary CNS ependymoma or embryonal tumors with leptomeningeal enhancement on MRI concerning for metastatic disease. Brain MRI with contrast for each patient was reviewed by a neuro-radiologist (BD) to evaluate enhancement of the IAC and its characteristics. Kaplan Meier survival analyses were conducted to compare progression free survival (PFS), event free survival (EFS), and overall survival (OS) between those with IAC enhancement and those without. Univariate analyses were also conducted to evaluate outcomes of various MRI characteristics of the IAC enhancement, including location (aperture, apex, both), laterality (bilateral, unilateral), enhancement type (linear, nodular) and outcome in follow-up MRIs (resolved, stable, enlarged). RESULTS The cohort included 58 patients with leptomeningeal enhancement, 25 of which had IAC enhancement. The presence of IAC enhancement was not significantly associated with OS, PFS or EFS, however nodular IAC enhancement was significantly associated with both progression (p<0.001) and death from disease (p=0.009) compared to linear IAC enhancement. No other analyses yielded statistically significant results. CONCLUSION Our findings highlight that nodular IAC enhancement is a potential prognostic marker for patients with metastatic CNS tumors. Multivariate analyses are warranted to clarify the robustness of this finding and will be performed on this cohort of patients.