Diagnostic Work-Up of Small Bowel Adenocarcinoma

• The differential diagnosis of a small bowel mass:
  • Is extensive
• Focal small bowel wall thickening can be present in:
  • Bowel ischemia
  • Inflammation:
    • Inflammatory bowel disease
  • Infection
  • Radiation enteritis
  • In addition to small bowel neoplasms
• Many of these conditions can be confirmed or excluded by:
  • The history and physical examination
  • Imaging characteristics
  • Further studies:
    • Endoscopy
• True small bowel masses can:
  • Be either malignant or benign:
    • Malignant lesions include:
      • Adenocarcinoma (36.9% of the cases)
      • Carcinoid tumor (37.4% of the cases)
      • Gastrointestinal stromal tumor (8.4% of the cases)
      • Lymphoma (17.3% of the cases)
      • Metastatic disease

• The most common benign small bowel masses include:
  • Adenomas
  • Leiomyomas
  • Lipomas
• More rare benign small bowel masses include:
  • Fibromas
  • Desmoids
  • Hemangiomas
  • Hamartomas
  • Schwannomas
• Patients who present with:
  • Obstruction, bleeding, or perforation from a small bowel mass:
    • Typically require exploration and resection:
      • Regardless of the etiology of the mass:
        • Unless they are medically unfit for surgery
• Patients who are asymptomatic or present with mild symptoms from a small bowel mass:
  • Should be worked up further with:
    • Tumor markers
    • Endoscopic evaluation:
      • For biopsy and tattoo if the lesion is endoscopically accessible:
        • If the lesion is not endoscopically accessible:
          • Then surgical resection:
            • May be necessary for definitive diagnosis and treatment

Laboratory Test (Tumor Markers)

• Carcinoembryonic antigen (CEA):
  • Is not sensitive or specific:
    • For small bowel adenocarcinoma:
      • But is elevated in 30% to 44% of those with:
        • Advanced local or metastatic disease
• CA 19-9:
  • Is also elevated in 30 % to 40% of those with:
    • Advanced local or metastatic disease
• These markers (CEA and CA 19-9) are best used:
  • To raise suspicion:
    • In patients being worked up for small bowel adenocarcinoma
  • For surveillance:
    • In those in whom it is elevated before treatment
  • Given the high false negative rate:
    • They should not be used to rule out adenocarcinoma

Imaging Work-Up

• Imaging is critical to differentiate a malignant etiology of nonspecific gastrointestinal symptoms from other causes:
  • Nausea
  • Vomiting
  • Obstipation
  • Bleeding
• Upper Gastrointestinal Series / Small Bowel Follow-through:
  • An upper gastrointestinal series with small bowel follow-through has a relatively low sensitivity in the detection of small bowel tumors (< 60%):
    • It is most commonly obtained in patients with a small bowel obstruction:
      • To help ascertain the presence and location of a complete small bowel obstruction and may reveal:
        • Intussusception
        • Mucosal defect
        • Tumor / mass:
          • Which should prompt further (cross-sectional) imaging
• Computed Tomography Scan:
  • CT is useful to identify:
    • Small bowel masses
    • Nodal disease
    • Distant metastases
    • Alternative etiologies of abdominal symptoms
  • Its sensitivity in detection of primary small bowel adenocarcinomas is:
    • Approximately 80%
  • CT appearance of small bowel adenocarcinoma includes:
    • Demonstration of a discrete mass
    • Focal mural thickening
    • Small bowel obstruction
    • Intussusception without a clear associated mass

• PET can be useful to:
  • Identify occult metastatic disease
  • Increase the suspicion of malignancy:
    • In nonspecific small bowel abnormalities on CT
• Enterography:
  • Advanced cross-sectional imaging techniques, including:
    • CT and magnetic resonance enterography:
      • Can be more accurate than other imaging to confirm or exclude small bowel cancers:
        • However, they are not universally available and have not been well studied in this population
• Endoscopy:
  • Endoscopic diagnosis of small bowel adenocarcinoma:
    • Is often definitive:
      • But is limited by the location of the tumor:
        • Which must reside in an endoscopically accessible location
    • Because adenocarcinomas are mucosal tumors:
      • They can often be visualized endoscopically:
        • Assuming they can be reached
    • Endoscopy also allows biopsy to be performed and can tattoo a lesion that may not be visible externally during bowel resection
    • Standard upper endoscopy is most useful if the suspected small bowel tumor is in the:
      • Duodenum or proximal jejunum.
• Enteroscopy:
  • Enteroscopy refers to upper endoscopy beyond the range of standard endoscopy:
    • Into the proximal jejunum
  • Techniques employed to advance the endoscope include:
    • Push
    • Balloon
    • Intraoperative assistance
  • Advantages over standard endoscopy include:
    • Increased range:
      • 50 cm to 150 cm distal to the ligament of Treitz
        • Occasionally:
          • The entire small bowel can be visualized using:
            • Anterograde and retrograde (transanal) approaches
  • Disadvantages include:
    • Technical difficulty with a requisite learning curve
    • iIncreased rates of:
      • Pancreatitis
      • Perforation:
        • Over standard endoscopy
• Wireless video capsule endoscopy:
  • Wireless video capsule endoscopy is typically used to:
    • Identify the source of occult gastrointestinal bleeding:
      • But is infrequently used to visualize small bowel masses
    • It has a high false negative rate (19%):
      • In identifying small bowel masses:
        • As well as a 2% false positive rate
  • Wireless capsule endoscopy:
    • Also has no biopsy capability
    • Can become lodged in nearly obstructing or obstructed segments of bowel

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