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High-grade neuroepithelial tumor with BCOR exon 15 internal tandem duplication – a comprehensive clinical, radiographic, pathologic, and genomic analysis.

Brain Pathol. 2019 May 18;:

Authors: Ferris SP, Velazquez Vega J, Aboian M, Lee JC, Ziffle JV, Onodera C, Grenert JP, Saunders T, Chen YY, Banerjee A, Kline CN, Gupta N, Raffel C, Samuel D, Ruiz-Diaz I, Magaki S, Wilson D, Neltner J, Al-Hajri Z, Phillips JJ, Pekmezci M, Bollen AW, Tihan T, Schniederjan M, Cha S, Perry A, Solomon DA

Abstract
High-grade neuroepithelial tumor with BCOR exon 15 internal tandem duplication (HGNET BCOR ex15 ITD) is a recently proposed tumor entity of the central nervous system (CNS) with a distinct methylation profile and characteristic genetic alteration. The complete spectrum of histologic features, accompanying genetic alterations, clinical outcomes, and optimal treatment for this new tumor entity are largely unknown. Here, we performed a comprehensive assessment of ten new cases of HGNET BCOR ex15 ITD. The tumors mostly occurred in young children and were located in the cerebral or cerebellar hemispheres. On imaging all tumors were large, well-circumscribed, heterogeneous masses with variable enhancement and reduced diffusion. They were histologically characterized by predominantly solid growth, glioma-like fibrillarity, perivascular pseudorosettes, and palisading necrosis, but absence of microvascular proliferation. They demonstrated sparse to absent GFAP expression, no synaptophysin expression, variable OLIG2 and NeuN positivity, and diffuse strong BCOR nuclear positivity. While BCOR exon 15 internal tandem duplication was the solitary pathogenic alteration identified in six cases, four cases contained additional alterations including CDKN2A/B homozygous deletion, TERT amplification or promoter hotspot mutation, and damaging mutations in TP53, BCORL1, EP300, SMARCA2, and STAG2. While the limited clinical follow-up in prior reports had indicated a uniformly dismal prognosis for this tumor entity, this cohort includes multiple long-term survivors. Our study further supports inclusion of HGNET BCOR ex15 ITD as a distinct CNS tumor entity and expands the known clinicopathologic, radiographic, and genetic features. This article is protected by copyright. All rights reserved.

PMID: 31104347 [PubMed – as supplied by publisher]

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