A case of multiple synchronous lung adenocarcinomas with differing EGFR mutations

We report a case of four synchronous lung cancers, each with a different epidermal growth factor receptor (EGFR) mutation in the tyrosine kinase domain. Bilateral double lung cancer was diagnosed clinically, and a left upper lobectomy and partial left S6 resection were performed. Right S1 segmental resection was performed later. Pathological examination revealed three lung adenocarcinomas in the left lung (S1 + 2, S3, and S6) and one in the right. Three different mutations of EGFR were identified with the polymerase chain reaction and direct sequencing of DNA from the three left lung tumors. The EGFR mutation on the right also differed from that of the left lung tumors.