HGG-19. H3- AND IDH-WILDTYPE DIFFUSE PAEDIATRIC-TYPE HIGH-GRADE GLIOMA WITHMYCN-AMPLIFICATION: AN INDICATION CRITERION FOR LI-FRAUMENI SYNDROME TESTING

Abstract

Abstract BACKGROUND: In the current World Health Organization (WHO) Classification of Tumors of the Central Nervous System (CNS) (5th edition), the introduction of a molecular layer to the integrated diagnosis not only helps to characterize and prognosticate paediatric CNS tumors but the molecular alteration may predict a potential therapeutic option with a targeted agent. Furthermore, certain gene alterations may be a presage of germline alterations or cancer predisposition syndromes, portending significant implications to the index patients and their families. We report a 5-year-old boy diagnosed with non-metastatic left hemispheric H3-wildtype and IDH-wildtype diffuse paediatric-type high-grade glioma with MYCN-amplification, who was subsequently found to have Li-Fraumeni syndrome. He presented with a 3-day history of facial asymmetry, unsteady gait and right sided weakness. There was no family history of malignancy. Initial MRI revealed a restricting and enhancing solid cystic lesion (5.9 x 4.3 x 5.8cm) in the left frontal-temporal-parietal region. Tumor debulking was performed. Histopathological examination by the local pathologist revealed features of high-grade glioma. Second pathology review with next generation sequencing confirmed H3-wildtype and IDH-wildtype diffuse paediatric-type high-grade glioma with MYCN-amplification and TP53 p.Y103* mutation. He was started on focal radiotherapy and oral temozolomide but succumbed to local and metastatic progressive disease. After genetic counselling, his DNA extracted from blood was sent for targeted exome sequencing and germline mutation of TP53 was demonstrated. Cascade screening of the family members were negative of TP53 mutation. Guerrini-Rousseau et al reported that 57% (n=7) of H3-wildtype and IDH-wildtype diffuse paediatric-type high-grade glioma with MYCN-amplification harboured germline TP53 pathogenic variants. This case further highlights the importance of screening of Li-Fraumeni syndrome in patient with H3-wildtype and IDH-wildtype diffuse paediatric-type high-grade glioma with MYCN-amplification even in the absence of a family history.