Molecular defects in BRAF wild-type ameloblastomas and craniopharyngiomas-differences in mutation profiles in epithelial-derived oropharyngeal neoplasms.

The aim of this study was to evaluate the mutation profile of BRAF wild-type craniopharyngiomas and ameloblastomas. Pre-screening by immunohistochemistry and pyrosequencing for identifying BRAF wild-type tumors was performed on archived specimens of ameloblastic tumors (n = 20) and craniopharyngiomas (n = 62). Subsequently, 19 BRAF wild-type tumors (nine ameloblastic tumors and ten craniopharyngiomas) were analyzed further using next-generation sequencing (NGS) targeting hot spot mutations of 22 cancer-related genes. Thereby, we found craniopharyngiomas mainly CTNNB1 mutated (8/10), including two FGFR3/CTNNB1-double mutated tumors. Ameloblastic tumors were often FGFR2 mutated (4/9; including one FGFR2/TP53/PTEN-triple mutated case) and rarely CTNNB1/TP53-double mutated (1/9) and KRAS-mutated (1/9). In the remaining samples, no mutation could be detected in the 22 genes under investigation. In conclusion, mutation profiles of BRAF wild-type craniopharyngiomas and ameloblastomas share mutations of FGFR genes and have additional mutations with potential for targeted therapy.