Progressive neuroendocrine tumor of lung with combined categories in metastatic site: a case report.

Background: Both large cell neuroendocrine carcinoma (LCNEC) and small cell lung carcinoma (SCLC) are high-grade neuroendocrine tumors of lung in classification. Combined LCNEC and combined SCLC may comprise up to 25% of the resected cases. However, co-existence of LCNEC and SCLC in lung accompanied with combined LCNEC in extrapulmonary metastatic sites is infrequent. Case Description: In this paper, we report a 58-year-old male with cough, back pain and increased sputum. He was diagnosed as LCNEC and SCLC in his lung successively. His tumor gradually progressed and combined LCNEC was then diagnosed in his cervical lymph node. Regimens of chemotherapy were accordingly adjusted several times, but his lesions were not relieved and he finally died. Conclusions: Both LCNEC and SCLC have high aggressiveness. Some patients may have limited curative effect and poor prognosis when treated with chemotherapy even in combination with immune checkpoint inhibitors. Combined LCNEC may occur in extrapulmonary sites of some patients when the tumor progresses. Timely radiological evaluations are essential to identify changes of pulmonary and extrapulmonary lesions. Histopathological results including morphological features of malignant cells and immunohistochemical features of diseased tissues are more indispensable in establishing a confident diagnosis of lung neuroendocrine tumor and judging corresponding cellular types.