NFS-03. Identification of BAP1 germline mutation in young patient with facial nerve meningioma underscores the critical importance of extensive genomic evaluations in clinical practice.

Abstract Objective To raise awareness about the significance of comprehensive germline and somatic genetic sequencing in cases with unusual presentation. Emphasized the stepwise surgical planning to maximize facial muscles innervation to optimize aesthetic outcomes. Background Facial nerve meningiomas are extremely rare in children. Clinical and/or pathology-driven tumor genetic testing and imaging are common diagnostic approaches, but germline mutations analysis critical for patient management and familial risk assessment may get overlooked. BAP1 tumor predisposition syndrome, caused by mutations in the BAP1 gene, increases the risk for multiple tumor types, including meningioma. Designs/Methods A case report and review. Case Presentation We report the case of a 14-year-old female who presented with left-sided tinnitus. She was found to have a facial nerve tumor on imaging, presumed to be a schwannoma. Initial germline genetic testing with schwannomatosis panel was negative. Surveillance MRIs over three years showed gradual tumor growth accompanied by left-sided hearing loss and partial facial nerve dysfunction. A stepwise surgical approach to maximize aesthetics consisting of facial nerve reinnervation by masseteric facial nerve transfer, and right to left cross facial nerve graft was performed followed by facial nerve rehabilitation and omplete tumor removal. On pathology the tumor was consistent with meningioma, meningothelial type WHO grade 1. Comprehensive paired tumor-normal sequencing revealed a pathogenic germline variant in BAP1 (c. 122GT) and a Tier 2 somatic variant in PBMR1 (c. 3263₃269delinsA). The identification of the mutation enabled preventive care, genetic testing for at-risk relatives, and tailored screening protocols for other cancers. Conclusion The identification of a BAP1 germline mutation in our case highlights the importance of comprehensive somatic and germline genomic evaluations. Such evaluations help detect underlying genetic syndromes, guide treatment, and enhance preventive care. A stepwise surgical planning is crucial for optimal facial nerve function and quality of life.