Clear cell carcinoma of the lung: a case report and review of the literature.

Clear cell carcinoma of the lung is an extremely rare type of lung cancer with doubtful etiology. This present case showed that the tumor cells contained abundant cytoplasmic glycogen with a diffusely distributed pattern and intracellular glandular structure electron microscopically. Immunohistochemical study revealed that the tumor cells expressed not only epithelial marker including cytokeratin and epithelial membrane antigen, but also Ley, one of stage-specific embryonic carbohydrate antigens. The diagnosis of pulmonary clear cell carcinoma should be done carefully, because benign clear cell tumor and secondary renal cell carcinoma show similarities in a histologic appearance but not in their management and prognosis.