The main difficulty with multiple lung tumors is distinguishing synchronous and metachronous lesions from second independent primary tumors, particularly when dealing with the same histologic type. Challenging diagnostic hurdles may explain, at least in part, the extremely variable (0%-79%) 5-year survival rate. We present a case report of a patient with synchronous primary adenocarcinoma treated with surgery that exhibited different EGFR gene status, with an exon 19 mutation in the adenocarcinoma of the left upper lobe that was absent in the right upper lobe. Further, specific EGFR and C-MYC amplification events were associated only with the EGFR-mutated lesion. According to an independent evolution theory, these events were classified as early stage, and the patient is still alive and free of disease 70 months after surgery. Molecular evaluation was an important tool to support the diagnosis of synchronous primary adenocarcinoma, which had not been possible with the application of Martini-Melamed criteria.