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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.

Purpose: To observe the clinicopathological, immunohistochemical, and molecular genetic features of epithelioid glioblastoma (E-GBM), and identify tumor-associated prognostic factors. Patients and Methods: The clinical and radiological data of fifteen cases of E-GBM were collected, and their pathological, immunohistochemical, and molecular features were examined. A 1p/19q analysis via FISH, MGMT promoter methylation by MS-PCR, and IDH1 and BRAF V600E mutation analysis by HRM-PCR were performed. The level of EZH2 expression was valuated by immunohistochemistry in 15 E-GBM cases, and the prognostic factors were analyzed in E-GBM patients. Fifteen non-E-GBM cases were used as a control. Results: The fifteen cases of E-GBM included twelve males and three females, with fourteen cases supratentorially located. Headache was the main symptom. Microscopy revealed that the tumors were composed of epithelioid cells and some rhabdoid cells. The epithelioid and rhabdoid cells displayed focal discohesion, scant intervening neuropil, a distinct cell membrane, eosinophilic cytoplasm, and a laterally positioned nucleus. Most tumors showed high mitosis, zonal necrosis, and microvascular hyperplasia. Immunohistochemical findings included epithelioid cells positive for GFAP, vimentin, nestin, S-100, and INI-1. The molecular findings included no deletions of 1p/19q, EGFR amplifications, or IDH1 mutations in any case, a methylated MGMT promoter in 46.7% (7/15) cases, and a BRAFV600E mutation in 46.7% (7/15) cases. EZH2 overexpression occurred in 60.0% (9/15) of E-GBM cases. E-GBM patients with OS (≤ 12 months) exhibited extensive necrosis (6/6), EZH2 overexpression (6/6), MGMT promoter unmethylation (5/6), BRAFV600E mutation (3/6), and treatment (surgery4/6). E-GBM patients with OS (> 12 months) exhibited focal or limited necrosis, low or negative EZH2 expression, MGMT promoter methylation (2/3), BRAFV600E mutation (3/3), and treatment (surgery+radiotherapy/chemo-radiotherapy, 2/3). Conclusion: E-GBM was a rare variant of glioblastoma, with histological epithelioid features and poor prognosis. Extensive necrosis, MGMT promoter unmethylation, EZH2 overexpression, and lack of adjuvant chemo-radiotherapy may indicate a poor prognosis. [ABSTRACT FROM AUTHOR]