10018-CS-4 A case of glioma with discordant radiological, histopathological, and genetic Findings

Abstract Introduction We report a case of glioma presenting with discordant findings across imaging, histopathology, and genetic testing. Case presentation A 30-year-old woman suffered from headache and nausea. Neurological examination revealed a left lower quadrant visual field defect and mild left hemispatial neglect. Brain MRI demonstrated a ring-enhanced mass with marked peritumoral edema in the right parietal lobe. Partial tumor resection was performed with the aid of a navigation system. Permanent pathology revealed a diagnosis of oligodendroglioma, NOS. Immunohistochemistry showed ATRX positivity, TP53 was nearly negative, IDH was wild-type, and the Ki-67 labeling index was 2%. MLPA analysis showed no EGFR amplification, no + 7/-10 chromosomal pattern, no PDGFRA or MYCN amplification. The tumor was H3-wildtype and IDH-wildtype, with no MGMTp methylation, no TERTp mutation, and no CDKN2A deletion. Due to radiological suspicion of high-grade glioma (HGG), treatment was initiated with the Stupp regimen. During the maintenance phase of temozolomide (TMZ), the patient became pregnant, and TMZ maintenance was paused for eight months. After childbirth, TMZ maintenance therapy was resumed. Two years have passed since the initial surgery, there has been no evidence of tumor recurrence. Discussion Even when imaging findings are not suggestive of oligodendroglioma, a diagnosis can still be made when histopathological and genetic findings are concordant. In this case, the tumor was IDH-wildtype, making oligodendroglioma unlikely, and 1p/19q codeletion status was not investigated. On the other hand, there have been reports describing oligodendroglial components within glioblastomas. It is possible that the sampled tissue represented an oligodendroglial component, while the main tumor mass was glioblastoma. However, for a glioblastoma with IDH-wildtype and unmethylated MGMTp, the clinical course without recurrence is unusually favorable. For a definitive diagnosis, DNA methylation profiling would be desirable. Conclusion We report a case of glioma with a challenging and inconclusive diagnosis.