ICD-10 C45.9
Billable / Specific HCC v28: 9Mesothelioma, unspecified
About ICD-10-CM C45.9
ICD-10-CM code C45.9 represents Mesothelioma, unspecified. This is a billable/specific code in the Neoplasms chapter (block C45). The 2026 edition of ICD-10-CM C45.9 became effective on October 1, 2025.
Coding Tips for C45.9
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
C45.9 is a CMS-HCC v28 risk-adjustment code (category 9). 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.
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 C45.9
Local Coverage Determinations (LCDs) from CMS MACs that list C45.9 as a covered diagnosis.
Showing top 10 of 464 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing C45.9.
5 Medicare
CPT Codes Commonly Billed with C45.9
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 77063 CMS LCD: Billing and Coding: Breast Imaging Mammography/Breast Echography (Sonography)/Breast MRI/Ductography CMS LCD
- 19030 CMS LCD: Billing and Coding: Breast Imaging Mammography/Breast Echography (Sonography)/Breast MRI/Ductography CMS LCD
- 76641 CMS LCD: Billing and Coding: Breast Imaging Mammography/Breast Echography (Sonography)/Breast MRI/Ductography CMS LCD
- G0279 CMS LCD: Billing and Coding: Breast Imaging Mammography/Breast Echography (Sonography)/Breast MRI/Ductography CMS LCD
- 77048 CMS LCD: Billing and Coding: Breast Imaging Mammography/Breast Echography (Sonography)/Breast MRI/Ductography CMS LCD
- 77047 CMS LCD: Billing and Coding: Breast Imaging Mammography/Breast Echography (Sonography)/Breast MRI/Ductography CMS LCD
- 77054 CMS LCD: Billing and Coding: Breast Imaging Mammography/Breast Echography (Sonography)/Breast MRI/Ductography CMS LCD
- C8906 CMS LCD: Billing and Coding: Breast Imaging Mammography/Breast Echography (Sonography)/Breast MRI/Ductography CMS LCD
- 76642 CMS LCD: Billing and Coding: Breast Imaging Mammography/Breast Echography (Sonography)/Breast MRI/Ductography CMS LCD
- 77067 CMS LCD: Billing and Coding: Breast Imaging Mammography/Breast Echography (Sonography)/Breast MRI/Ductography CMS LCD
Convert C45.9 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 |
|---|---|---|
| C45.9 | 1991 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To C45.9
Other codes in section C45-C49 (Malignant neoplasms of mesothelial and soft tissue).
ICD-10 C45.9, Billing FAQ
Is ICD-10 code C45.9 billable? +
Yes, C45.9 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
Does C45.9 affect Medicare Advantage HCC risk adjustment? +
Yes. C45.9 maps to CMS-HCC v28 category 9. Capture this diagnosis annually for accurate Medicare Advantage risk score.
What CPT codes are commonly billed with C45.9? +
Procedures frequently paired with C45.9 include: 77063, 19030, 76641, G0279, 77048.
What ICD-9 codes does C45.9 map to? +
Per CMS GEMs, C45.9 maps to ICD-9 codes: 1991. 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 May 31, 2026.
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