C18 vs C49.A

C18 (Malignant neoplasm of colon) compared with C49.A (Gastrointestinal stromal tumor), from the official CMS tabular data. Both may be reported when both conditions are documented (Excludes2).

Can these codes be reported together?

Yes, when both are documented. C18 carries an Excludes2 note covering C49.A: “gastrointestinal stromal tumors (C49.A-)”

Excludes2 marks distinct conditions — both may be reported when both are documented.

Side by side

	C18Malignant neoplasm of colon	C49.AGastrointestinal stromal tumor
Billing status	Non-billable header Report instead: C18.0, C18.1, C18.2, C18.3, C18.4	Non-billable header Report instead: C49.A0, C49.A1, C49.A2, C49.A3, C49.A4
Classification	C00-D49 — Neoplasms (C00-D49)	C00-D49 — Neoplasms (C00-D49)
Definition	Malignant neoplasm of colon is a non-billable ICD-10-CM category code (C18).	Gastrointestinal stromal tumor is a non-billable ICD-10-CM category code (C49.A).
Includes	—	malignant neoplasm of blood vessel malignant neoplasm of bursa malignant neoplasm of cartilage malignant neoplasm of fascia

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Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources