Endobronchial large cell neuroendocrine carcinoma.

Lung tumors with neuroendocrine morphology include typical carcinoid, atypical carcinoid, large cell neuroendocrine carcinoma, and small cell carcinoma. The World Health Organization emphasizes the importance of mitotic count in differentiating these tumors. We studied the case of a 58-year-old male nonsmoker with recurrent pneumonia and an endobronchial mass, which was removed by right middle lobectomy. The patient was alive with no recurrent disease at 36-month follow-up. Histologically, the tumor showed well developed neuroendocrine morphology but contained up to 20 mitoses per 10 high-power fields and was therefore diagnosed as a large cell neuroendocrine carcinoma. However, several features, including the carcinoid-like morphology and endobronchial location of the tumor, absence of smoking history, and promising clinical course, were more characteristic of an atypical carcinoid than of a large cell neuroendocrine carcinoma. It may be necessary to redefine histologic criteria to allow a higher mitotic rate for classification as an atypical carcinoid.