A bone metastasis of non-small cell lung carcinoma with prominent clear cell features.

We report the case of a 78-year-old man with multiple bone tumours and three round, smooth nodules in the right lung. He was referred to our hospital because of the left femoral neck pathological fracture. The histological characteristics of the femoral tumour corresponded to clear cell carcinoma, and bone and lung lesions were regarded as metastatic from an unknown primary site, since there was no clinical evidence of renal carcinoma. His general conditions gradually declined, and he died 2 months after the operation. At autopsy, no neoplasia lesion was found in the kidneys. Although clear cell components were histologically dominant in the affected organs such as the lungs, bones and liver, neoplastic tubular structures also existed. Immunohistochemically, atypical cells were positive for napsin-A. The final diagnosis was adenocarcinoma of the lung origin with prominent clear cell features.