BRAF AND HISTONE 3 ALTERATIONS IN THE INTEGRATED DIAGNOSIS OF PEDIATRIC GLIAL AND GLIONEURONAL TUMORS: A SINGLE CENTER EXPERIENCE

CARDOSO NAZARENA; COLLI S; MASSONE C; CORES M; GARCIA LOMBARDI, M.; DE MATTEO E; ALEJANDRO, LORENZETTI MARIO; MARIA VICTORIA PRECIADO

Congreso; Reunión Anual Sociedades de Biociencia. SAIC. SAI. SAFIS; 2021

While tumors of the central nervous system account for over 20% of pediatric tumors, gliomas represent more than 55% of them. Their classification into low (LGG) or high grade gliomas (HGG) may reflect survival odds. Molecular techniques enable more accurate diagnostic results and risk stratification. Molecular alterations in BRAF gene and histone 3 genes (H3) were evaluated by FISH, IHC and Sanger sequencing, in 102 pediatric glial and glioneuronal tumors. BRAF and/or H3 were assessed in LGG or HGG according to WHO recommendations. Results were correlated with clinical and histological findings to evaluate them as diagnostic and prognostic tools.The KIAA1549-BRAF gene fusion was relevant as a diagnostic tool for Pilocytic astrocytoma, a LGG,(43/64 cases), but was not related to progression free survival (PFS) and overall survival (OS) (Kaplan Meier, Log-rank (Mantel-Cox) Test; P>0.05). This fusion showed no association with different age groups (10 < years old ≥ 10, Fisher's exact test; P>0.05), but was more prevalent in the cerebellum (Chi square test; P=0.04). The BRAFV600E mutation occurred preferentially in the brain hemispheres 7/10 cases (Fisher´s exact test; P=0.004) and was associated with a shorter OS (P=0.0082), but not with a decreased PFS (P=0.14) in LGG. When only considering Pilocytic astrocytomas, it was associated with a decreased OS and PFS (P