Diffuse peritoneal metastases from primary colon cancer demonstrated by Tc-99m-labeled red blood cell scintigraphy

An 80-year-old man, who underwent complex abdominal surgery for left colon cancer 2 years earlier, was hospitalized because of severe anemia and recurrent episodes of melena. Esophagogastroduodenoscopy and colonoscopy did not reveal abnormal findings. Abdominal ultrasonographic examination and computed tomographic scan failed to detect tumor recurrence or metastatic lesions but moderate ascites was found. Tumoral marker serum levels were abnormal. Tc-99m red blood cell scintigraphy was performed and disclosed a potential site of intestinal hemorrhage: both dynamic and static images showed a slight but diffuse and persistent uptake of Tc-99m erythrocytes in the entire abdomen with no clear evidence of a site of active bleeding. These findings suggested diffuse peritoneal micrometastases, which were confirmed at autopsy.