Abstract
BackgroundDiffuse midline gliomas with the H3K27M mutation are now recognized as separate entities due to their unique molecular signature, clinical features, and adverse outcome.ObjectiveTo determine the morphological spectrum and survival rate of diffuse midline gliomas with H3K27M mutation.Material and methodsThis retrospective study was conducted between January 2015 and January 2021 at Shaukat Khanum Memorial Cancer Hospital and Research Centre. Medical records of 28 cases of H3K27M-mutated midline gliomas were retrieved. Case slides were reviewed and the pertinent histological spectrum was evaluated.ResultsThe mean age of patients was 24.36 ± 14.06 years. There were 21 (75%) males and 7 (25%) females. Biopsy was performed in 22 (78.6%), total resection in 1 (3.6%) while subtotal resection was done in 5 (17.9%) cases. Histologically, a spectrum of morphologies was noted with pilocytic astrocytoma (WHO grade 1) at one end and glioblastoma (WHO grade IV) at the other end. Immunohistochemically, all 28 cases were positive for Histone 3 immunohistochemistry. ATRX was performed in 7 (25.0%) cases with loss of ATRX expression in 3 (10.7%) and retained expression in 4 (14.3%) cases. Ki67 was <5% in 6 (21.4%), 5-10% in 1 (3.6%), 11-15% in 1 (3.6%), 16-20% in 3 (10.7%), 21-25% in 4 (14.3%), and 26-30% in 2 (7.1%) cases. The mean survival was 8.00 ± 9.39 months. Out of 28 patients, 15 (62.5%) patients died of disease.ConclusionDiffuse midline gliomas with H3K27M mutation is an aggressive entity with a broad morphological spectrum.
Highlights
Gliomas are the most frequent primary tumors of the CNS and encompass two principal subgroups: diffuse gliomas and gliomas showing a more circumscribed growth pattern [1]
Due to their unique molecular signature and clinical features, diffuse midline gliomas with H3K27M mutation are recognized as a separate entity in the 2016 WHO Classification of Tumors of the CNS
H3K27M mutation was initially described in the pediatric age group, but afterward, it was observed in the adult population [4]
Summary
Gliomas are the most frequent primary tumors of the CNS and encompass two principal subgroups: diffuse gliomas and gliomas showing a more circumscribed growth pattern (non-diffuse gliomas) [1]. Modern diagnostic amendments have received greater attention in the last few years and the histological diagnosis of brain tumors is being made in combination with molecular testing. This has resulted in the emergence of novel entities like "diffuse midline gliomas with H3 K27M mutation" [3]. Due to their unique molecular signature and clinical features, diffuse midline gliomas with H3K27M mutation are recognized as a separate entity in the 2016 WHO Classification of Tumors of the CNS. Diffuse midline gliomas with the H3K27M mutation are recognized as separate entities due to their unique molecular signature, clinical features, and adverse outcome
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