A case of synchronous metastasis of breast cancer to stomach and colon.

A case of synchronous metastasis of breast cancer to the stomach and colon is reported. A 38-year-old woman with a history of bilateral breast cancer was admitted for endoscopic examination because of occult blood. Endoscopic examination showed elevated lesions on the mucosal surface of the stomach and cecum. Histopathological examination of the biopsy specimens obtained from both sites showed adenocarcinoma, comprised of tumor cells with structural and nuclear atypia, which were similar to those of the primary breast cancer cells. In immunohistochemical analysis, these tumor cells stained positive for ER. Therefore, we diagnosed a synchronous metastasis of breast cancer to the stomach and colon. Synchronous metastasis of breast cancer to the stomach and colon without liver metastasis or peritoneal dissemination is extremely rare, with only 4 reported cases existing in literature.