Gastrointestinal Stromal Tumor (GIST), Leiomyomas, & Leiomyosarcomas

• • Radiographic or endoscopic evidence of gastric mass

  • Often accompanied by upper GI bleeding

Epidemiology

• • Represent 1% of all GI malignancies

  • -Stomach is most common site

  • Difficult to distinguish malignant from benign histologically

  • Increased size (> 6-10 cm) correlates with increased risk of malignancy

  • In most cases, the tumor arises from the proximal stomach

  • -Benign tumors more common on lesser curvature

    -Malignant tumors more common on greater curvature

  • Tumors may grow into the gastric lumen, remain entirely on the serosal surface, or even become pedunculated within the abdominal cavity

  • Spread is by direct invasion or blood-borne metastases

  • -Liver most common site of metastases

Symptoms and Signs

• • Often asymptomatic

  • May present with occult or apparent GI bleeding (melena, hematochezia)

  • Weight loss

  • Nausea and vomiting may be present if tumor obstructs gastric outlet

  • Epigastric mass palpable in 20% of patients

Laboratory Findings

• • Anemia

Imaging Findings

• • Radiology and endoscopy: Tumor usually contains a central ulceration caused by necrosis from outgrowth of its blood supply

  • CT scans: Provide useful information on the amount of extragastric extension

• • Contrast radiography or upper GI endoscopy will reveal a gastric mass

  • Endoscopic biopsy that penetrates through the gastric mucosa will usually provide diagnosis but not distinguish benign from malignant

Rule Out

• • Adenocarcinoma

  • Lymphoma

  • Other gastric neoplasm

• • Contrast radiography or upper GI endoscopy will reveal a gastric mass

  • Endoscopic biopsy, perhaps guided by endoscopic US, will usually be diagnostic

  • CT scans provide useful information on the amount of extragastric extension

  • Hgb to assess anemia and treat accordingly

When to Admit

• • Severe anemia or apparent upper GI hemorrhage

  • High-grade obstruction

• • Leiomyomas: Enucleation or wedge resection (2-3 cm margin)

  • Leiomyosarcomas: More radical gastric resection

Surgery

Indications

• • All leiomyomas and leiomyosarcomas

  • Complete resection of metastases in addition to the primary may improve the outcome

Medications

• • Imatinib mesylate

Complications

• • GI bleeding

  • Gastric outlet obstruction

Prognosis

• • GIST: 5-year survival rate is 20-55% after resection

  • Tumors with 10 or more mitoses in a high-powered field rarely can be cured

References