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Tumor of small intestine

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small intestine cancer types symptoms diagnosis treatment NCI

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Tumors of the Small Intestine

Small-intestinal tumors are rare, accounting for less than 5% of gastrointestinal cancers. They are often diagnosed late because symptoms can be vague or absent. - Mulholland and Greenfield’s Surgery, p. 2540

Types

Benign
  • Adenoma
  • Lipoma
  • Hamartoma, including Peutz-Jeghers polyps
  • Leiomyoma
  • Desmoid tumor
Malignant
  1. Adenocarcinoma
    • Epithelial malignancy, usually in the duodenum or proximal jejunum.
    • Risks: Crohn disease, celiac disease, familial adenomatous polyposis, Lynch syndrome, Peutz-Jeghers syndrome.
    • May cause annular narrowing and intestinal obstruction.
  2. Neuroendocrine tumor (NET, previously carcinoid)
    • Common in the ileum.
    • Can be small but still metastasize, especially to mesenteric lymph nodes and liver.
    • May produce desmoplastic reaction causing bowel obstruction or ischemia.
    • Carcinoid syndrome, flushing, diarrhea, bronchospasm, usually occurs with liver metastases.
  3. Lymphoma
    • Usually non-Hodgkin lymphoma.
    • Associated with celiac disease, immunodeficiency, and inflammatory bowel disease.
    • May present with abdominal pain, bleeding, perforation, or obstruction.
  4. Gastrointestinal stromal tumor (GIST)
    • Mesenchymal tumor arising from interstitial cells of Cajal.
    • Typically associated with KIT or PDGFRA mutations.
    • Can present with bleeding, mass, or pain; metastases are commonly hepatic or peritoneal.
      • Mulholland and Greenfield’s Surgery, pp. 2540-2541
  5. Sarcomas
    • Includes leiomyosarcoma, now much less frequent than GIST.
The major malignant groups are adenocarcinoma, NET, lymphoma, and GIST. - Harrison’s Principles of Internal Medicine, p. 694. The NCI classification also includes sarcomas among small-intestinal cancers.

Clinical features

  • Intermittent, cramping abdominal pain
  • Nausea, vomiting, and intestinal obstruction
  • Occult or overt gastrointestinal bleeding
  • Iron-deficiency anemia
  • Unexplained weight loss and anorexia
  • Palpable abdominal mass
  • Intussusception, especially with a polyp or benign lead point
  • Perforation, particularly with lymphoma or adenocarcinoma
Positive fecal occult blood, unexplained anemia, and small-bowel obstruction are common routes to diagnosis. - Harrison’s Principles of Internal Medicine, p. 694

Diagnosis

  • CT abdomen/pelvis or CT enterography
  • MR enterography, particularly useful for small-bowel lesions
  • Upper GI endoscopy for duodenal tumors
  • Capsule endoscopy for mucosal lesions or obscure bleeding, but avoid if obstruction is suspected due to capsule retention risk
  • Device-assisted enteroscopy or double-balloon enteroscopy for direct visualization and biopsy
  • Histopathology and immunohistochemistry
  • For NET: somatostatin-receptor imaging such as Ga-68 DOTATATE PET/CT
  • Staging with CT or MRI, assessment of liver and nodal metastases
Capsule endoscopy can help detect lesions but cannot obtain tissue; deep enteroscopy permits biopsy and lesion marking before surgery. - Mulholland and Greenfield’s Surgery, p. 2540

Treatment

Treatment depends on histology, location, resectability, and metastatic spread.
Tumor typeMain treatment
AdenomaEndoscopic removal if feasible; surgery for large, multiple, or complicated lesions
Localized adenocarcinomaSegmental resection with regional lymph-node removal
Localized NETSurgical resection of primary tumor and mesenteric nodes where appropriate
LymphomaSystemic chemotherapy or immunochemotherapy; surgery mainly for bleeding, obstruction, or perforation
Resectable GISTSurgical resection without routine lymph-node dissection
High-risk/metastatic GISTTargeted therapy, commonly imatinib when mutation profile supports it
Advanced NETSomatostatin analogues, liver-directed treatment, peptide receptor radionuclide therapy, or systemic therapy depending on grade and extent
Surgery is the principal potentially curative treatment for resectable small-intestinal cancers. For lymphoma, surgery is generally reserved for complications. - Mulholland and Greenfield’s Surgery, p. 2540; the NCI treatment summary describes resection and bypass procedures for obstruction.

Important examination points

  • Most common site of adenocarcinoma: duodenum/proximal jejunum
  • Common malignant tumor of ileum: neuroendocrine tumor
  • GIST marker/mutation: KIT (CD117), often KIT or PDGFRA mutation
  • Celiac disease association: enteropathy-associated T-cell lymphoma and small-bowel adenocarcinoma
  • Common presentations: obstruction, bleeding, anemia, weight loss, pain
  • Definitive diagnosis: histopathological examination of biopsy or resected specimen
Seek prompt medical assessment for persistent abdominal pain with vomiting, black or bloody stool, iron-deficiency anemia, unintended weight loss, or symptoms of bowel obstruction.
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