A RARE CASE OF PEDIATRIC MN1 ALTERED ASTROBLASTOMA WITH CONCOMITANT ATM GERMLINE MUTATION

Astroblastoma is a rare brain tumor that has recently emerged as a new entity in the 2021 WHO classification of tumors of the central nervous system (CNS), based on its peculiar histopathologic feature and association with MN1 alteration. We report an unique case of MN1- altered astroblastoma with concomitant ATM germline mutation. A 10-year-old girl presented with nausea and vomiting due to a large temporal parietal tumor. Gross total resection was achieved and the integrated molecular diagnosis of MN1 -altered astroblastoma was made based on DNA methylation profiling. Next-Generation Sequencing (NGS) confirmed a MN1-BEND2 fusion and germline sequencing revealed an ATM gene heterozygous pathogenic variant. Radiation therapy was deferred given the possible association of heterozygous ATM mutation with increased risk of breast cancer and radiosensitivity. This case highlights the therapeutic implications of germline molecular findings in the treatment of astroblastoma and the need for further investigations to define a more standardized approach for treating this rare pediatric tumor.