Coexistence of multiple liver metastases from sigmoid colon cancer and a gastrointestinal stromal tumor in the small intestine.

A 60-year-old man was referred to our hospital for the evaluation and treatment of general malaise. Contrast-enhanced computed tomography detected sigmoid colon cancer that had invaded the bladder, multiple liver metastases, and a small intestinal tumor. Hartmann's procedure was performed, with partial bladder and small bowel resection. A pathological examination revealed that the patient had sigmoid colon cancer and a gastrointestinal stromal tumor. The biopsy findings of a tumor in segment 8 of the liver indicated the presence of adenocarcinoma, thereby indicating the origin of multiple liver metastases from sigmoid colon cancer. On chemotherapy, the tumors in liver segments 2/3 and 8 shrank. However, the tumor in segment 6 enlarged. Since radical resection of all metastatic liver tumors was possible, hepatectomy was performed 10 months after the initial surgery. A pathological examination revealed that the tumors in segments 2/3, 4, and 8 were adenocarcinomas and the tumors in segments 4, 6, and 7 had originated from the gastrointestinal stromal tumor. This suggested the coexistence of liver metastases from sigmoid colon cancer and the gastrointestinal stromal tumor. In cases involving multiple primary tumors, it is necessary to consider the possible coexistence of multiple metastases from different primary tumors.