ICD-10 C26.9
Billable / Specific HCC v28: 11Malignant neoplasm of ill-defined sites within the digestive system
About ICD-10-CM C26.9
ICD-10-CM code C26.9 represents Malignant neoplasm of ill-defined sites within the digestive system. This is a billable/specific code in the Neoplasms chapter (block C26). The 2026 edition of ICD-10-CM C26.9 became effective on October 1, 2025.
Coding Tips for C26.9
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
C26.9 is a CMS-HCC v28 risk-adjustment code (category 11). To count for the patient Risk Adjustment Factor (RAF), document the diagnosis with MEAT language each calendar year: Monitored, Evaluated, Assessed, Treated. A diagnosis on the problem list alone does not satisfy CMS RADV audit standards. Include the diagnosis in the assessment with current status and current treatment plan.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under C26.9. Per CMS ICD-10-CM Tabular 2026.
- Malignant neoplasm of alimentary canal or tract NOS
- Malignant neoplasm of gastrointestinal tract NOS
Type 1 Excludes
Pure excludes, these codes can never be coded together with C26.9. The conditions are mutually exclusive (e.g., congenital vs acquired forms).
- malignant neoplasm of abdominal NOS (C76.2)
- malignant neoplasm of intra-abdominal NOS (C76.2)
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Medicare LCD Coverage for C26.9
Local Coverage Determinations (LCDs) from CMS MACs that list C26.9 as a covered diagnosis.
Showing top 10 of 484 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing C26.9.
2 Cigna
5 Medicare
CPT Codes Commonly Billed with C26.9
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 81540 CMS LCD: Billing and Coding: MolDX: bioTheranostics Cancer TYPE ID� Update CMS LCD
- 45341 CMS LCD: Billing and Coding: Colonoscopy and Sigmoidoscopy-Diagnostic CMS LCD
- 45331 CMS LCD: Billing and Coding: Colonoscopy and Sigmoidoscopy-Diagnostic CMS LCD
- 45337 CMS LCD: Billing and Coding: Colonoscopy and Sigmoidoscopy-Diagnostic CMS LCD
- 45332 CMS LCD: Billing and Coding: Colonoscopy and Sigmoidoscopy-Diagnostic CMS LCD
- 45334 CMS LCD: Billing and Coding: Colonoscopy and Sigmoidoscopy-Diagnostic CMS LCD
- 45335 CMS LCD: Billing and Coding: Colonoscopy and Sigmoidoscopy-Diagnostic CMS LCD
- 45342 CMS LCD: Billing and Coding: Colonoscopy and Sigmoidoscopy-Diagnostic CMS LCD
- 45330 CMS LCD: Billing and Coding: Colonoscopy and Sigmoidoscopy-Diagnostic CMS LCD
- 45338 CMS LCD: Billing and Coding: Colonoscopy and Sigmoidoscopy-Diagnostic CMS LCD
Convert C26.9 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| C26.9 | 1598 | 10000 |
| C26.9 | 1599 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To C26.9
Other codes in section C15-C26 (Malignant neoplasms of digestive organs).
ICD-10 C26.9, Billing FAQ
Is ICD-10 code C26.9 billable? +
Yes, C26.9 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What other names or terms map to C26.9? +
ICD-10 C26.9 includes: Malignant neoplasm of alimentary canal or tract NOS; Malignant neoplasm of gastrointestinal tract NOS.
What codes are Type 1 Excludes for C26.9? +
Type 1 Excludes (never code together with C26.9): malignant neoplasm of abdominal NOS (C76.2); malignant neoplasm of intra-abdominal NOS (C76.2)
Does C26.9 affect Medicare Advantage HCC risk adjustment? +
Yes. C26.9 maps to CMS-HCC v28 category 11. Capture this diagnosis annually for accurate Medicare Advantage risk score.
What CPT codes are commonly billed with C26.9? +
Procedures frequently paired with C26.9 include: 81540, 45341, 45331, 45337, 45332.
What ICD-9 codes does C26.9 map to? +
Per CMS GEMs, C26.9 maps to ICD-9 codes: 1598, 1599. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on July 17, 2026.
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