C49.A9
BillableGastrointestinal stromal tumor of other sites
HCC Category Mapping
V28HCC 23 — Melanoma and Other Skin Cancers
0.251V24HCC 10 — Lymphoma and Other Cancers
0.675ESRDHCC 10 — Lymphoma and Other Cancers
0.000RxHCCHCC 20 — Cancer, Liver and Intrahepatic Bile Duct
0.000What This Code Means
A gastrointestinal stromal tumor located in other parts of the digestive system not specified by the more specific codes.
Coding Tips
- •Use this code for GIST in sites such as the stomach, small intestine, or other GI locations
- •Document the specific anatomical site in the medical record for clarity and future reference
Clinical Significance
Gastrointestinal stromal tumor of other sites captures GISTs occurring in uncommon locations such as the mesentery, omentum, or extraintestinal sites. While rare (approximately 5% of GISTs), extra-gastrointestinal GISTs (eGISTs) share the same molecular biology and targeted therapy responsiveness as typical GISTs.
Documentation Requirements
- ✓Pathology confirming GIST with immunohistochemistry at an atypical site
- ✓Specific anatomical site documented (mesentery, omentum, peritoneum, etc.)
- ✓Verification that the site is not better classified under C49.A1-C49.A5
- ✓Tumor size, mitotic rate, and mutation analysis
- ✓Distinction from other soft tissue sarcomas at the same site
Commonly Confused Codes
C49.A0 (GIST, unspecified site) — C49.A9 is for a KNOWN site that is 'other,' not for unknown sitesC49.A1-C49.A5 (Site-specific GIST codes) — verify the site is not better classified under a more specific codeC48._ (Malignant neoplasm of retroperitoneum/peritoneum) — non-GIST malignancies of these sitesC49.4 (Soft tissue of abdomen) — general soft tissue sarcoma, not specifically GIST