Epithelioid glioblastoma arising from pleomorphic xanthoastrocytoma with the BRAF V600E mutation

Abstract

Pleomorphic xanthoastrocytoma (PXA) is classified by the World Health Organization as a grade II astrocytic tumor with relatively favorable prognosis among gliomas. A valine-to-glutamic acid substitution at position 600 of the serine/threonine-protein kinase BRAF (BRAF V600E) mutation, which is commonly found in PXA, has recently been detected in approximately 50% of all epithelioid glioblastoma (GBM) cases. We herein report a case of epithelioid GBM developing at the site of a left temporal PXA 13 years after the treatment of the primary tumor. The BRAF V600E mutation was detected in both tumors. These findings suggest that epithelioid GBM may arise from a PXA with a BRAF V600E mutation.

Epithelioid Glioblastomas and Anaplastic Epithelioid Pleomorphic Xanthoastrocytomas—Same Entity or First Cousins?

“…Furthermore, methylome analysis showed that one of our four tested eGBMs had a methylation pattern that clustered with conventional PXA. Lastly, a case recently reported by Tanaka et al (26) showed an eGBM developing within the tumor bed of a PXA 13 years after initial resection.All these data suggest that eGBM and ePXA are either the same entity or highly related.…”

“…In our practice, we have occasionally encountered PXAs with anaplastic transformation showing cytologic characteristics that are indistinguishable from those of eGBM. In a similar fashion, a case report of eGBM arising in a PXA has recently been reported (26). As with eGBM, PXAs with anaplastic transformation most often afflict children and young adults, although cases in older patients have also been reported (3,15).…”

Epithelioid glioblastoma, a newly described rare variant of common tumor describing immunohistochemical expression pattern

“…[6] Similarly, Tanaka et al also described a case of Ep-GBM arising in a patient diagnosed with PXA 13-years after the treatment. [7] Considering the above two examples it seems that Ep-GBMs are closely related with PXA which is a low grade glial tumor in comparison to conventional GBMs. However, since Ep-GBM has poor outcomes than typical GBM as well as uncertain response to temozolamide, this hypothesis is questionable and needs further evaluation.…”

Diagnostic algorithms for astrocytic brain tumors in adults according to revised classification of central nervous system tumors.

“…Пропозиції доповнити класифікацію гліоб-ластом епітеліоїдним варіантом лунали з 1998 року [20], стримувалися відносно незначним від-сотком цих пухлин, але зараз стало відомо, що ця група пухлин демонструє молекулярні зміни, характерні для дитячих форм астроцитом, а саме плеоморфної ксантоастроцитоми (мутація гену BRAF), що дозволяє припустити особливий он-тогенез [21,22].…”