Abstract
We report a case of colonic metastasis initially suspected of being primary colon cancer following surgery for Stage IA gastric cancer. A 69-year-old man with gastric cancer who underwent distal pyloric gastrectomy in March 2007 was found pathologically to have highly atypical cancer cells diagnosed as Stage IA cancer (por1 with sig, pT1 (SM2), pN0, sH0, sP0, and sM0). CEA gradually increased postoperatively to 9.4 ng/ml eight months later, at which point positron-emission tomography indicated a mass in the ascending colon. Colonoscopy showed an ulcerous lesion suggested by biopsy to be poorly differentiated adenocarcinoma subsequently diagnosed as primary ascending-colon cancer necessitating right colectomy in January 2008. This was rediagnosed as gastric cancer metastasis based on pathological findings and cytokeratin-immunostaining. Colonic metastasis of Stage IA gastric cancer, which is early-stage, is extremely rare and no other such cases have, to our knowledge, been reported in Japan. Even early-stage gastric cancer can be highly malignant and metastatic when cancer cells are highly atypical, as this case suggests.
