Clinical characteristics and imaging features of small bowel adenocarcinomas in Crohn's disease

Small bowel adenocarcinoma is uncommon in patients with Crohn's disease but has an extremely poor prognosis. There is a paucity of data on the clinical characteristics and radiologic features of this entity. We sought to update our institutional experience with small bowel adenocarcinoma occurring in the setting of Crohn's disease and to systematically re-examine pre-operative imaging findings.

Medical records were abstracted to identify all patients with Crohn's disease and small bowel adenocarcinoma who were evaluated at Mayo Clinic, Rochester, Minnesota and Mayo Clinic, Scottsdale, Arizona between 1976 and 2012. Clinical, demographic, and outcomes data were obtained for each patient. Pre-diagnosis radiologic imaging was re-evaluated by two gastrointestinal radiologists.

Thirty-four patients (21 males) were identified. Median ages at Crohn's disease and cancer diagnoses were 22.4 and 52.9 years, respectively. Median follow-up after cancer diagnosis was 272.0 days; 22 patients (64.7%) had persistent or recurrent adenocarcinoma at last follow-up. 1- and 2-year mortality rates were 29.6% and 48.0%. Pre-operative imaging studies were available for re-review in 14 cases. Features concerning for malignancy included annular mass, nodularity at the extraluminal margins of the mass, and perforation. Nearly all tumors arose in regions of chronic inflammation and caused luminal narrowing with pre-stenotic dilatation.

Small bowel adenocarcinoma is rare in patients with Crohn's disease but results in significant mortality. CT or MR imaging findings can be suggestive of the pre-operative diagnosis, but it is usually diagnosed at an advanced stage with laparotomy.