Rare metastasis of primary bronchogenic carcinoma to sigmoid colon: report of a case.

The authors present a case of a rare metastasis of bronchogenic carcinoma to sigmoid colon. Carcinoma of the lung usually spreads locally to adjacent mediastinum or paratracheal lymph nodes via the lymphatics. When tumor invades the pulmonary vein, distal metastases are most often to brain, suprarenal glands, or bones. Primary bronchogenic carcinoma has been reported to metastasize to jejunum, maxillary antrum, small bowel, tongue, and rarely to other organs. The authors believe that metastasis to the large intestine is most exceptional. Occurrences of rare metastasis are not well understood, though one theory implicates sites of previous trauma.