C49.A3

HCC Category Mapping

What This Code Means

A gastrointestinal stromal tumor (GIST) is a rare type of cancer that develops in the small intestine from specialized nerve cells in the digestive tract. These tumors can vary in size and aggressiveness, and may require surgery or targeted medication treatment.

Coding Tips

• •Verify the tumor location is specifically the small intestine (duodenum, jejunum, or ileum) before assigning this code; other GI locations have different codes
• •Check documentation for tumor behavior (benign vs. malignant) and stage if available, as this code represents the malignant variant; ensure any associated treatment codes align with cancer diagnosis

Clinical Significance

Gastrointestinal stromal tumor of the small intestine is the second most common GIST location (20-25% of cases) and carries a worse prognosis than gastric GISTs of comparable size and mitotic rate. Small intestinal GISTs are more likely to present with gastrointestinal bleeding or obstruction and often require surgical resection.

Documentation Requirements

• ✓Pathology confirming GIST of small intestinal origin with immunohistochemistry
• ✓Specific segment involved (duodenum, jejunum, or ileum)
• ✓Tumor size and mitotic rate for risk stratification (small bowel GISTs have higher risk at smaller sizes)
• ✓Presenting symptoms (bleeding, obstruction, perforation)
• ✓KIT/PDGFRA mutation testing results for targeted therapy planning

Commonly Confused Codes