adenocarcinoma of the small bowel

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

Pathology

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 ileum.

Risk factors include a history of:

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

Radiographic features

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

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

Differential diagnosis

Small bowel malignant tumors:

Small bowel benign tumors:

  • adenomatous polyp
  • villous adenoma
  • leiomyoma
  • lipoma
  • hamartoma
  • hemangioma