A Case of Peritoneal Abscess Due to Colon Penetration by a Fish Bone

We report a case of peritoneal abscess due to colon penetration by a fish bone, which was preoperatively diagnosed by CT. An 88-year-old woman referred for an abdominal tumor with dull upper abdominal pain was found in abdominal CT to have a tumor in the right upper abdomen. Gastrointestinal and colon endoscopy showed no abnormality. Following the administration of antibiotics for a right knee injury, abdominal pain improved and the abdominal tumor shrank. Follow-up abdominal CT confirmed tumor shrinkage and the presence of a calcified linear foreign body. The patient was followed up and soon after discharge, the abdominal tumor greu and abdominal pain recurred. Resection of the tumor and transverse colon showed a fish bone to be present in the abscess.