MDB-91. MEDULLOBLASTOMA – MOLECULAR CHARACTERISTICS AND RADIOLOGICAL ASPECTS OF A BRAZILIAN COHORT FROM A SINGLE CENTER

Abstract BACKGROUND Four molecular subgroups of medulloblastoma are distinguished by their genomic, epidemiological, and prognostic characteristics: Wingless (WNT), Sonic hedgehog (SHH), Group 3 and Group 4. Genotypic classification permits individualized therapeutic planning based on risk stratification, thereby improving patient outcome. This study aims to characterize the epidemiological and molecular data of a cohort treated at a single Brazilian center, as well as to correlate the heterogeneous aspects of magnetic resonance imaging (MRI) with the molecular characteristics of this tumor. METHODS The study analyzed 47 medulloblastoma cases, treated at the children’s oncology reference institution of a middle-income country between 2011 and 2021. The medical records, radiological findings and the histological and molecular classification are reviewed. The images were evaluated by an experienced neuroradiologist, blinded to clinical and molecular information. RESULTS Thirty-two out 47 patients met the eligibility criteria and were analyzed. The frequency of molecular groups found was 6.25% Non-SHH/ Non-WNT, 12.50% WNT, 34.38% SHH, 3% Group 3 and 44 % Group 4. The analysis revealed tumor location, presence of hemorrhage/calcification, limits and enhancement patterns are significant for molecular group prediction. SHH shows a significant prevalence in the cerebellar hemisphere, lower presence of hemorrhage/calcification and an ill-defined tumor margins when compared with other subgroups. Group 4 showed significantly less enhancement. CONCLUSIONS In accordance with the frequency observed in studies on childhood medulloblastoma, our series found a significant prevalence of Group 4 and a lack of representativeness of Group 3. Despite the limitations, it was possible to identify radiological tumor characteristics that may predict the molecular subgroup and contribute to a more effective therapeutic approach, thereby reducing the incidence of post-surgical complications.