Pulmonary clear cell carcinoma.

A case of pulmonary clear cell carcinoma is demonstrated. A large left lower lobe mass, without lymphadenopathy was detected on a screening chest X-ray, and a left lower lobectomy was performed. The tumor was composed predominantly of clear cells with some areas showing cells typical for small cell carcinoma. Ultrastructurally, the larger clear cell had cytoplasm containing many rough endoplasmic reticuli and free ribosomes, while the smaller dark cell showed a serrated nucleus and scanty cytoplasm having many free ribosomes without neurosecretory granules. This is the first report on pulmonary clear cell carcinoma with small cell carcinoma patterns, and this case will throw doubt on the conclusion of previous studies that clear cell carcinoma is not a separate entity.