A woman in her 50s was admitted to our hospital with fever and lower abdominal swelling. Abdominal CT/MRI examinations revealed irregular thickening of the transverse colon wall, which was attached to a subcutaneous abscess. An abdominal wall mass, a patent urachus, and a tumor in the 5th segment of the liver were also noted. Colonoscopy revealed type 2 advanced transverse colon cancer. The solitary, sessile tumor was observed at the apex of the bladder under cystoscopy, suggesting the formation of the urachal carcinoma. Transcutaneous liver biopsy obtained from the liver tumor indicated adenocarcinoma, which was morphologically different from the existing transverse colon cancer. Right hemicolectomy with resection of the umbilicus, abdominal wall, urachus, and part of the bladder wall was performed. Diagnosis of the transverse colon cancer invading the abdominal wall and bladder was confirmed by histopathological examination. Hepatectomy was performed in the next surgery, and the tumor was histopathologically diagnosed as an intrahepatic cholangiocarcinoma. Both the transverse colon cancer and the intrahepatic cholangiocarcinoma were radically resected. Radical surgical diagnostic resection may be valuable in cases of multicentric cancers of unknown primary origin, if radical resection of each individual tumor is required.