A145 ENDOSCOPICALLY NON-VISIBLE INTERVAL COLONIC ADENOCARCINOMA DESPITE HIGH-QUALITY SURVEILLANCE.

Abstract

\n \n \n Colonoscopy remains the gold-standard for screening and surveillance of colorectal cancer (CRC). Regular colonoscopy with polypectomy has been associated with reduced CRC incidence and mortality. However, interval CRC, defined as cancer diagnosed between initial screening and subsequent surveillance colonoscopies, occurs at rates of 2–14%. Identified risk factors for interval cancers include patient-related factors (older age, diverticular disease, proximal CRC), endoscopy-related factors (colonoscopy by non-gastroenterologists or in an outpatient setting; endoscopists with low rates of completion, adenoma detection or polypectomy) and biologic factors (microsatellite instability (MSI), CpG island methylation). We report a patient with interval metastatic ileo-cecal adenocarcinoma despite multiple, high-quality surveillance colonoscopies, not endoscopically visible as no visible intra-luminal mucosal component was present.\n \n \n \n To describe a case of an interval CRC without an endoscopically visible intra-luminal component.\n \n \n \n Case description and literature review.\n \n \n \n A 69-year-old male, with a history of multiple advanced colonic polyps requiring multiple surveillance colonoscopies and polypectomies, presented with symptoms of bowel obstruction. An abdominal CT scan revealed findings of terminal ileitis and upstream small bowel obstruction. Colonoscopy was performed, revealing obstruction of the ileo-cecal valve with a firm cecal submucosal lesion without abnormal overlying mucosal abnormalities. Exploratory laparoscopy revealed a mass at the ileo-cecal valve with associated peritoneal deposits. A right hemicolectomy was performed, and pathological examination demonstrated metastatic invasive adenocarcinoma involving the cecum, the terminal ileum and ileo-cecal valve without extension into the lumen or formation of an overt polypoid mass. The tumour extended into the wall of the distal ileum in a circumferential fashion, involving the immediate deep serosa, but with only minimal, focal mucosal ileal involvement and no overt polypoid mass. An independent review of the case and resection specimen by a second pathologist confirmed absence of significant ileal or colonic mucosal involvement and no obstructing intraluminal component.\n \n \n \n This case illustrates a rare presentation of an interval CRC that was not identified despite several high-quality surveillance colonoscopies, as only minimal mucosal involvement was present. As endoscopy remains the gold-standard for early detection and removal of pre-malignant lesions and early malignancy, the patient’s presentation with interval malignant bowel obstruction and metastatic disease, despite adequate quality surveillance, demonstrates an inherent limitation of colonoscopy. To our knowledge, this is only the third documented case of endoscopically non-visible interval CRC.\n \n \n \n NoneNone\n