A clinicopathologic study of diencephalic pediatric low-grade gliomas with BRAF V600 mutation

Abstract Among brain tumors, the BRAF V600E mutation is frequently associated with pleomorphic xanthoastrocytomas (PXAs) and gangliogliomas (GGs). This oncogenic mutation is also detected in ~5 % of other pediatric low-grade gliomas (LGGs) including pilocytic astrocytomas (PAs) and diffuse astrocytomas. In the current multi-institutional study of 56 non-PXA/non-GG diencephalic pediatric LGGs, the BRAF V600 mutation rate is 36 %. V600-mutant tumors demonstrate a predilection for infants and young children (<age 3) and have a higher tendency for multicentricity. On neuroimaging, BRAF V600-mutant tumors appear as nodular, yet infiltrative contrast-enhancing masses. Morphologic examination reveals a monophasic, predominantly compact and partially infiltrative architecture. Due to the lack of classic morphologic features associated with PAs, pilomyxoid astrocytomas (PMAs), or diffuse astrocytomas, 75 % of the BRAF V600-mutant tumors could not be definitively classified on initial histopathologic evaluation. At a median follow-up of 55 months, the 5-year progression-free survival (PFS) rate for BRAF V600-mutant diencephalic low-grade astrocytomas (LGAs) was 22 ± 12 %, shorter than BRAF V600-WT PAs (52 ± 13 %) but higher than PMAs (10 ± 6 %). Of note, long-term PFS was observed in severa...
Source: Acta Neuropathologica - Category: Neurology Source Type: research