Synchronous primary lung cancer presenting with small cell carcinoma and adenocarcinoma

Multiple synchronous primary lung cancers presenting with different histologic types are uncommon. Among reported cases with different histologic findings, only a few had small cell lung cancer (SCLC) and adenocarcinoma. This unusual combination of lung cancers has not been well reported. In this report, we describe two cases of synchronous primary lung cancer presenting with lymph node metastasis of SCLC and early-stage adenocarcinoma. Epidermal growth factor receptor (EGFR) mutation was not detected in either SCLC or adenocarcinoma in the two cases.