Oncocytic carcinoid of the lung: A clinicopathologic study of three cases and review of the literature

Purpose To investigate the clinicopathologic features, biological behavior of oncocytic carcinoid tumor of the lung (OCTL) and its differentiated diagnosis. Methods Histopathologic, immunohistochemical stainings and ultrastructural observation were analyzed in three cases of OCTL. Results Men tended to possess, with patients′ age ranged from 16 to 80 years (average 49.9 years). The patients of OCTL were often cough and haemoptysis. Histopathologically, the tumor cells were round-oval, with abundant oncocytic granules in the cytoplasm by light-microscope. Immunohistochemical staining showed the tumor cells were positive for NSE, chromogranin A, synaptophysin and cytokeratins, and negative for S-100 protein. Ultrastructure observation showed characteristic neurosecretory granules and abundant mitochondria in tumor cells. Conclusions OCTL is a distinctive morphologically disease entity of neuroendocrine cancer. It can be differentiated from other pulmonary tumors based on immunohistochemical staining and ultrastructural examination, and the biological behavior is similar to atypical carcinoid.