Clinical and pathological features of IDH1-mutant glioblastoma: analysis of 10 cases

Abstract

Objective To investigate clinical and pathological features of IDH1-mutant glioblastoma (GBM IDH1-mut). Methods The clinical and radiological data of 10 patients with GBM IDH1-mut were collected, and their pathological, immunohistochemical, and molecular features were analyzed. The pathological diagnosis and molecular genetic features of GBM IDH1-mut were explored based on the findings in these cases and the previously reported cases. Results Of the 10 patients with GBM IDH1-mut (including 6 male and 4 female patients), 7 had temporal lobe involvement with headache and dizziness as the main symptoms. Pathological examination revealed that the tumors were highly cellular, and the tumor cells were pleomorphic (spherical, spindle-shaped and polygonal) with nuclear atypia and brisk mitotic activity. All the tumors showed microvascular proliferation and foci of necrosis. Microvascular hyperplasia was characterized mainly by a glomeruloid appearance; tumor necrosis, featured mostly by palisading necrosis and coagulative ischemic necrosis, could be either extensive or focal. The component of glioma (WHO Ⅱ/Ⅲ) was found in 8 cases. The tumor cells were immunohistochemically positive for GFAP, Nestin, and IDH1 in all the cases, and Olig-2 expression of varying intensity was found in 9 cases; diffuse expression of P53 was observed in 9 cases. ATRX was negative in all the cases. The tumor cells were negative for NeuN, NF, CD68, Syn, and CD34, and the microvascular endothelial cells were positive for CD34. All the tumors showed IDH1R132H mutation. MGMT promoter methylation was detected in 9 cases, and none of the cases showed loss of 1p/19q (0/4); TERT mutation or BRAFV600E mutation (0/3) was detected in none of the cases. Conclusion GBM IDH1-mut is rare. About half of the patients with GBM IDH1-mut have favorable prognoses, which may be related to focal necrosis and mild microvascular proliferation; the other half of the patients have poor prognoses possibly due to extensive necrosis and significant microvascular proliferation.

Keywords

• central nervous system tumor
• glioblastoma idh1-mutant
• immunohistochemistry
• clinicopathological features
• molecular genetics