ETMR-32. SUPRATENTORIAL NEUROEPITHELIAL TUMOR WITH PLAGL1 FUSION: A CASE REPORT

Abstract

Abstract BACKGROUND Supratentorial neuroepithelial tumor with PLAGL1 fusion has emerged as a novel subgroup within pediatric brain tumors. Despite its recent identification, critical aspects such as optimal clinical characteristics and management strategies remain elusive. This case report aims to contribute essential insights to the growing body of literature surrounding this enigmatic tumor entity, providing a detailed exploration of its clinical presentation and histopathological features. METHODS A retrospective chart review was conducted, and relevant data were analyzed. RESULTS An 11-year-old female presented with a two-week history of headaches, vomiting, lethargy, and decreased oral intake. Neuroimaging revealed a left frontal lesion with conspicuous mass effect and midline shift, prompting urgent craniotomy due to sudden onset altered mental status. Histopathological analysis revealed a hypercellular glial neoplasm characterized by perivascular pseudorosettes, scattered microcalcifications, microcysts, and areas of necrosis. Immunohistochemical staining revealed GFAP positivity in a substantial subset of tumor cells, rare dot-like positivity for EMA, and diffuse membranous and focal dot-like positivity for D240. Olig2 was mostly negative, indicating the absence of Oligodendrocyte lineage differentiation. The tumor exhibited an elevated Ki-67 proliferation index (approximately 20-30%). Fluorescence in situ hybridization (FISH) studies were negative for RELA, YAP1, and C19MC rearrangements. Targeted next-generation sequencing unveiled an EWSR1-PLAG1 fusion and methylation profiling classified the tumor as “Neuroepithelial tumors, PLAG1-fused” with high confidence. Given the morphological resemblance to anaplastic ependymoma, the therapeutic recommendation included focal irradiation (54 Gy) with proton therapy. The patient, now 12 months post-therapy, is showing favorable clinical outcomes. CONCLUSION This case report underscores the clinical and histopathological intricacies of supratentorial neuroepithelial tumors with PLAGL1 fusion. The identification of EWSR1-PLAG1 fusion and associated molecular alterations informs diagnostic considerations and treatment strategies for this novel entity, emphasizing the importance of continued research to enhance our understanding of its clinical behavior and optimal management approaches.