ICD-10 Code C49.A4 – Gastrointestinal stromal tumor of large intestine (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C49.A4 – Gastrointestinal stromal tumor of large intestine
What it is
This code identifies a gastrointestinal stromal tumor arising in the large intestine. It represents a mesenchymal neoplasm documented as originating in the colon or rectum, not a nonspecific abdominal mass.
Clinical signs
Clinical features vary; refer to documentation. Commonly recorded findings include a colorectal mass, abdominal pain, bleeding, anemia, or incidental imaging discovery, but you should code only when the provider specifies this tumor type and site.
When to use this code
Use C49.A4 when the record clearly states gastrointestinal stromal tumor of the large intestine, including colon or rectal involvement as documented. Apply it for confirmed diagnoses, pathology reports, or specialist notes that identify the tumor’s location. If the site is unclear, check documentation before coding.
Do not use for
Do not use this code for unspecified gastrointestinal stromal tumor, other digestive organ sites, or generic malignant neoplasm of the colon. If the provider documents a different primary site or only suspects GIST, verify the chart.
Coding tip
Match the exact anatomic site in the pathology or operative note, because GIST codes are site-specific.