Small Intestinal Neoplasms

Key Features

Essentials of Diagnosis

• Acute gastrointestinal (GI) bleeding with hematochezia or melena

• Chronic GI blood loss resulting in fatigue and iron deficiency anemia

• Obstruction resulting in vomiting

General Considerations

• Adenocarcinoma occurs most commonly in the duodenum

• Ampullary carcinoma incidence is increased > 200-fold in patients with familial adenomatous polyposis

• Nonampullary adenocarcinoma of the small intestine: majority have metastasized at the time of diagnosis

• Lymphoma may arise primarily in the GI tract or involve it secondarily in disseminated disease

  • In the United States, primary GI lymphoma accounts for 5% of all lymphomas and 20% of small bowel malignancies

  • Most common histologic subtype is non-Hodgkin extranodal marginal zone (MALT) B cell lymphoma

  • Enteropathy-associated T cell lymphoma (EATL)

    • Appears to be increasing in incidence in the United States

    • Is associated with the diagnosis of celiac disease

  • In the Middle East, lymphoma occurs in immunoproliferative small intestinal disease

• Carcinoid tumors account for one-third of small intestinal tumors

  • Carcinoid tumors derive from neuroendocrine cells and may or may not secrete a number of hormones, including serotonin or its precursors

  • Most are malignant, though many behave in an indolent fashion

  • Even small carcinoid tumors may metastasize, usually by extension to the local lymph nodes and to the liver

  • Carcinoid syndrome occurs in < 10% of patients, usually in patients with hepatic metastasis; caused by tumor secretion of hormonal mediators

• Most malignant sarcomas arise from stromal tumors that stain positive for CD117; Kaposi sarcoma is rare except in untreated AIDS

• Most benign small bowel polyps occur singly; multiple polyps suggest a hereditary polyposis syndrome

• Small bowel adenocarcinoma in young patients or those with a family history of gastrointestinal adenocarcinomas should prompt screening for Lynch syndrome (hereditary nonpolyposis colorectal cancer syndrome)

Clinical Findings

Symptoms and Signs

• Most small bowel cancers have already metastasized at the time of diagnosis

• Adenocarcinomas

  • Abdominal pain

  • Nausea

• Nonampullary adenocarcinoma of the small intestine

  • Obstruction

  • Acute or chronic bleeding

  • Weight loss

• Ampullary carcinoma

  • Jaundice due to common bile duct obstruction

  • Bleeding

• Primary lymphoma

  • Abdominal pain

  • Weight loss

  • Nausea and vomiting

  • Abdominal distention

  • Anemia

  • Occult blood in the stool

• Carcinoid tumors

  • Most asymptomatic

  • Carcinoids are generally indolent tumors that spread slowly

  • May present with intermittent abdominal pain, bowel obstruction, or bowel infarction

  • Manifestations of carcinoid syndrome: facial flushing, edema of the head and neck (especially with bronchial carcinoid), abdominal cramps and diarrhea, bronchospasm, cardiac lesions (pulmonary or tricuspid stenosis or regurgitation), and telangiectases

• Neuroendocrine tumors

  • Diarrhea

  • Flushing

  • Wheezing

Differential Diagnosis

• Crohn disease

Benign polyps

• Mucosal polyps: adenoma, hamartoma, hyperplastic

• Lipoma

• Benign stromal tumor (leiomyoma)

Malignant lesions

• Adenocarcinoma

• Lymphoma (primary or secondary)

• Carcinoid

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