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Question: What is a gastrointestinal stromal tumor (GIST), and how is it coded?

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Answer: GISTs are an uncommon form of cancer found in the gastrointestinal (GI) tract. They 鈥渟tart in very early forms of special cells in the wall of the GI tract called the interstitial cells of Cajal (ICCs),鈥� according to the .

You can use the following ICD-10-CM codes when your provider has specified a specific site for the GIST:

• C49.A1 (Gastrointestinal stromal tumor of esophagus)
• C49.A2 (Gastrointestinal stromal tumor of stomach)
• C49.A3 (Gastrointestinal stromal tumor of small intestine)
• C49.A4 (Gastrointestinal stromal tumor of large intestine)
• C49.A5 (Gastrointestinal stromal tumor of rectum)
• C49.A9 (Gastrointestinal stromal tumor of other sites)

You鈥檒l use C49.A9 if your provider indicates the GIST is in a GI structure rather than a specific anatomic site, as inclusion terms for the code include blood vessel, bursa, cartilage, fascia, fat, ligament except uterine, lymphatic vessel, muscle, synovia, and tendon (sheath). And if your provider has only indicated GIST in the patient鈥檚 notes, the default code to use is C49.A0 (Gastrointestinal stromal tumor, unspecified site). 

Most GISTs are malignant in nature. However, you can use D21.4 (Benign neoplasm of connective and other soft tissue of abdomen) for a benign GIST, as benign stromal tumors are listed as an inclusion term for the code.

Bruce Pegg, BA, MA, CPC, CFPC, Managing Editor, AAPC