A case of synchronous double primary lung cancer with neuroendocrine features.

We report a case of unique double primary lung cancers with neuroendocrine features in a 63-year-old male smoker. The mass in the left lower lobe (LLL) was a small cell/large cell carcinoma with spindle cell sarcomatous areas and organoid structure. The mass in the left upper lobe (LUL) was a tubular adenocarcinoma with neuroendocrine features including organoid nests showing occasional rosette formation, nuclear palisading in the periphery of the nests and positive immunoreaction for CD56, chromogranin A and synaptophysin. The difference in histological structures between the two masses led us to diagnose double primary lung cancer. The combination of small cell lung carcinoma and spindle cell carcinoma is very uncommon. The relationship between LLL and LUL tumors remains unclear. Multiple lung cancers with neuroendocrine features have only rarely been reported in the literature. The patient in our case died of widespread cancer 2 years and 4 months after the surgery without adjuvant chemotherapy, a longer postoperative survival time than in cases of ordinary extensive small cell lung cancer. Multiple lung cancers with neuroendocrine features are extremely rare and similar cases have not been reported in the literature. Neuroendocrine differentiation has attracted widespread attention and, therefore, examining neuroendocrine features in lung cancers is important.