Maxillary carcinosarcoma: Identification of a novel MET mutation in both carcinomatous and sarcomatous components through next generation sequencing

Background Carcinosarcoma is a rare tumor with biphasic growth of the carcinomatous and sarcomatous components. Prognosis is generally poor and characterization of the molecular mechanisms may provide information for the development of novel antitumor agents and biomarkers. Methods and Results We present the case of 66-year-old man with a complaint of nasal obstruction. He was diagnosed with maxillary carcinosarcoma and coexisting papilloma. He underwent multimodal treatment but died of uncontrolled local disease 10 months after the initial presentation. Genetic testing using next-generation sequencing (NGS) revealed that both the carcinomatous and sarcomatous components carried a somatic mutation in the conserved domain of the mesenchymal-epithelial transition factor (MET) proto-oncogene. Conclusion Our observation highlighted the importance of the MET gene in the oncogenesis of maxillary carcinosarcoma and is indicative of the common clonal origin of both malignant components. This suggested a possibility of treating MET mutation-positive carcinosarcomas with c-MET inhibitors.