Presumed Solitary Dissemination of Colon Cancer Mimicking Primary Cancer of the Small Intestine

A 69-year-old man with abdominal distention was referred to our hospital. The patient had undergone laparoscopic surgery for his Borrmann type 2 rectal cancer 2 years before. In addition to the re-elevation of serum CEA and CA19-9 levels, computed tomography (CT) showed intestinal dilatation, and positron emission CT showed a presumed tumor with abnormal fluorodeoxyglucose accumulation in the small intestine. We judged the small intestinal dilatation was highly due to the solitary recurrent peritoneal dissemination of rectal cancer and performed laparoscopic evaluation of the abdominal cavity followed by laparoscopic resection of the affected small intestine. The small intestinal tumor resembled the rectal cancer both on macroscopical and microscopical findings, that is, Borrmann type 2 phenotype and adenocarcinoma that was well differentiated in the part that protruded into the small intestinal lumen and whose degree of differentiation gradually decreased toward the serosa. In addition, abrupt disruption of the normal small intestinal epithelium and the lymphocytic aggregation, presumed tumor-infiltrating lymphocytes, just between the tumor and the small intestinal epithelium highly suggested the tumor originating from the colon cancer. The patient recovered uneventfully with marked decrease in tumor marker levels 1 month after the operation but did not receive colon cancer-oriented chemotherapy as adjuvant therapy for his financial reasons. Oncologists should note this type of recurrence to properly treat the patients with recurrent colorectal cancer. (C) 2021 The Author(s). Published by S. Karger AG, Basel