Surgical treatment for metastatic lung tumors with incidentally coexisting lung cancer.

We report four surgically resected cases of a metastatic lung tumors with incidentally coexisting lung cancer. Two patients (Cases 1 and 2) were admitted for surgical treatment for pulmonary metastases from colon cancer, and the other two (Cases 3 and 4) were for pulmonary metastases from renal cell carcinoma. In only one patient (Case 3), one lesion among the multiple shadows on the preoperative computed tomography examination was rather strongly suspected to be primary lung cancer. In three patients (Cases 1, 2 and 3), one of the resected lesions in each individual case was diagnosed as lung adenocarcinoma by an intraoperative examination using frozen sections, and was later histologically confirmed. In Case 4, one of the resected lesions was postoperatively determined to be lung adenocarcinoma. All coexisting lung cancers, treated with partial resection of the lung, were well-differentiated small-sized adenocarcinoma (T1N0), while the other lesions resected in each case were metastases from the individual cancer. Problems in preoperative diagnosis and surgical treatment for metastatic lung tumors with incidentally coexisting lung cancer are discussed.