Adenocarcinoma of the small bowel

Last revised by Michael P Hartung on 12 Oct 2023

Primary adenocarcinoma of the small bowel is about 50 times less common than colonic carcinoma.

Almost 50% of small bowel adenocarcinomas are found in the duodenum, especially near the ampulla. In the remaining cases, the jejunum is more commonly involved than the ileum1.

Risk factors include a history of:

More distal small bowel adenocarcinomas are more likely to be annular, duodenal adenocarcinomas tend to be papillary or polypoid1.

CT shows a soft-tissue mass with heterogeneous attenuation, usually with moderate enhancement after intravenous administration of contrast material.

The mass may manifest as an annular narrowing with abrupt concentric or irregular “overhanging edges,” a discrete tumor mass or an ulcerative lesion.

Usually, only a short segment of the bowel is involved. Gradual narrowing of the lumen leads to partial or complete small bowel obstruction 1.

A large, aggressive, ulcerated adenocarcinoma can be mistaken for lymphoma. However, lymph node metastases in adenocarcinoma are usually less bulky than those in lymphoma.

Small bowel malignant tumors:

Small bowel benign tumors:

  • adenomatous polyp

  • villous adenoma

  • leiomyoma

  • lipoma

  • hamartoma

  • hemangioma

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