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Abstract Giant cell glioblastoma (GC-GBM) is a malignant infiltrating astrocytic tumor, characterized by highly atypical large cells with pleomorphic nuclei, numerous multinucleated GCs, necrosis, microvascular proliferation, and brisk mitotic activity. It is placed under the subcategory of GBM and is classified as central nervous system (CNS) World Health Organization (WHO) grade 4 tumor, with very poor prognosis. Unlike most of the other CNS neoplasms, its signature molecular cytogenetic abnormality is not well known and our knowledge is restricted to case reports and small case series. This study encompasses the clinicopathological and molecular profile of GC-GBM cases diagnosed in our institute over a period of 10 years (2014–2023). A retrospective review of medical records (2014–2023) was performed and 256 cases of GBM were selected. Among these, 11 (4.3%) cases were diagnosed as GC-GBM. The clinical and histopathological features were studied. Hematoxylin and eosin slides were reviewed and immunohistochemistry was performed. Immunohistochemical markers included glial fibrillary acidic protein (GFAP), IDH1 R132H, TP53, and Ki-67. The mean age of study patients was 29.4 years with a male:female ratio of 1.75:1. All the tumors were supratentorial in location and the most common site was the frontoparietal lobe. On histology, presence of numerous GCs admixed with bizarre astrocytic cells, brisk mitoses, microvascular proliferation, and necrosis were consistent features. On immunohistochemistry, GFAP positivity was observed in all the cases, IDH1 R132H immunoreactivity in 5 cases, TP 53 mutation in 10 cases, and Ki67% was > 10% in all the cases. GC-GBM is a rare subtype of GBM with unique histopathology and a relatively better prognosis, but its molecular biology still remains unresolved. Our study highlights the hybrid nature of this rare tumor sharing characteristics of both wild-type GBM, isocitrate dehydrogenase (IDH) wild-type, CNS WHO grade 4, and astrocytoma, IDH mutant, CNS WHO grade 4 (previous secondary GBM).
Gupta et al. (Tue,) studied this question.