A rare case of gallbladder cancer with multiple metastases to the colon.

Gallbladder cancer is often diagnosed with metastasis and is known to have poor prognosis. Although, gallbladder cancer often metastasizes to liver, lung, or lymph nodes, metastasis to gastrointestinal tract is not common. Several autopsy studies reported colorectal metastasis from gallbladder cancer, but most of these cases were supposed to be gastrointestinal invasion from peritoneal dissemination. We experienced a rare case of hematogenous colon metastasis from gallbladder cancer. Colonoscopy for a 76-year-old man who was diagnosed as gallbladder cancer revealed two 5-mm flatly elevated lesions with central erosion in the transverse and sigmoid colon. Endoscopic mucosal resection (EMR) revealed poorly differentiated adenocarcinoma in hematoxylin and eosin staining. Additional immunohistochemistry examination showed strongly positive CK7 expression with negative CDX2, and suggested colon metastases from gallbladder cancer. Despite the positive vertical margin in EMR specimens, autopsy finding denied colorectal invasion from peritoneal dissemination and proved vascular spread colon metastases. Gastrointestinal metastasis is often misdiagnosed as a primary tumor, and thus, it is important to recognize gallbladder cancer as a potential origin of gastrointestinal metastasis.