Oncocytic carcinoma of lung: a clinicopathological observation

Objective To investigate the clinicopathological features of oncocytic carcinoma of the lung.Methods A case of oncocytic carcinoma of the lung was studied by light microscopy,electron microscopy,immunohistochemical stains and review of the literature.Results Histopathologically,the tumor showed no capsule,invasive growth and significant necrosis.The tumor was mostly composed of cells with eosinophilic granules in the cytoplasm,obvious cell and nuclear polymorphism.Immunohistochemically,the tumor cells were positive for CK,whereas EMA,Syn,CgA,and S-100 protein were negative.Ultrastructurally,the oncocytic cells showed large numbers of mitochondria but no neurosecretory granules. Conclusion Pulmonary oncocytic carcinoma is an extremely rare malignant tumor.Morphologically,it is necessary to differentiate from oncocytic carcinoid tumor,oncocytoma,and metastatic oncocytic carcinoma.Immunohistochemical stains and electronic microscopy play important roles in the diagnosis and differential diagnosis.