C45.9 — Mesothelioma, unspecified
C45.9 is a billable, specific ICD-10-CM code for mesothelioma, unspecified. It is valid for submission on a claim.
Other codes that can never be billed with C45.9
These codes carry an Excludes1 note pointing at C45.9. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading C45.9 alone.
Risk adjustment
C45.9 risk-adjusts. Under the CMS-HCC V28 model it maps to this category:
- HCC 19 Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers1.798 RAF
Coefficient shown for the Community Non-dual Aged segment. A higher HCC in the same hierarchy will suppress this one, so capturing it does not always add score.
Medicare coverage
C45.9 is named in 56 Medicare coverage policies — 56 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A52450Billing and Coding: Paclitaxel (e.g., Taxol®/Abraxane ™)
- A52479Oral Anticancer Drugs - Policy Article
- A52479Oral Anticancer Drugs - Policy Article
- A52479Oral Anticancer Drugs - Policy Article
How C45.9 is indexed
Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to C45.9.
- Mesothelioma(malignant)
- Mesothelioma›biphasic
- Mesothelioma›epithelioid
- Mesothelioma›fibrous
- Mesothelioma›site classification›unspecified
Code history
C45.9 has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.
Related codes at this level
Codes that share C45. If C45.9 is not quite right, the correct code is usually one of these.
Questions about C45.9
- Is C45.9 a billable ICD-10-CM code?
- Yes. C45.9 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does C45.9 sit in the tabular list?
- Neoplasms (C00-D49), in the block Malignant neoplasms of mesothelial and soft tissue (C45-C49).