A case of ganglioglioma grade 3 withH3 K27Mmutation arising in the medial temporal lobe in an elderly patient

Abstract

The mutation p.K27M inH3F3A(H3K27M mutation) is mainly detected in diffuse midline glioma. However, recent studies have demonstrated thatH3K27M mutation could also be observed in a subset of gangliogliomas. Importantly, mostH3K27‐mutated ganglioglioma cases also harborBRAFV600E mutation. Herein, we report a rare case ofH3K27M‐mutated ganglioglioma grade 3 withoutBRAFmutation arising in the medial temporal lobe in an elderly man. A small biopsy specimen was sampled. The pathological diagnosis was diffuse astrocytoma. The tumor progressed gradually during an 18‐month follow‐up period. Gadolinium enhancement on magnetic resonance imaging was noted 36 months after the biopsy. The patient was referred to a hospital for tumor resection. Histological analysis of resected specimens led to a diagnosis of ganglioglioma grade 3 with H3 K27M mutation. The patient underwent concurrent temozolomide chemotherapy with radiotherapy. Although the patient's condition deteriorated after chemotherapy due to disease progression, he survived for more than 23 months after tumor resection. We present this rare case and discuss the involvement ofH3K27M mutation in ganglioglioma grade 3.