2026 ICD-10-CM Diagnosis Code C45.2Mesothelioma of pericardium
ICD-10-CM Codes›C00–D49›C45-C49›C45
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 19
- Chronic Condition
C45.2 is a billable ICD-10-CM diagnosis code for mesothelioma of pericardium. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 314 through 316. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 2 closely related codes. Coders also document this condition as malignant mesothelioma of pericardium. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Mesothelioma.
For Medicare Advantage risk adjustment, C45.2 maps to CMS-HCC Category 19 (Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers) under the V28 model, adding a risk factor of about 1.798 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
C45.2 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Malignant mesothelioma of pericardium
- Malignant neoplasm of pericardium
- Neoplasm of mesothelial tissue of pericardium
- Primary malignant mesothelioma of pericardium
- Primary malignant neoplasm of pericardium
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Type 1 Excludes
- other malignant neoplasm of pericardium C38.0
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Mesothelioma
a tumor derived from mesothelial tissue (peritoneum, pleura, pericardium). it appears as broad sheets of cells, with some regions containing spindle-shaped, sarcoma-like cells and other regions showing adenomatous patterns. pleural mesotheliomas have been linked to exposure to asbestos. (dorland, 27th ed)Mesothelioma, Cystic
a peritoneal mesothelioma affecting mainly young females and producing cysts of variable size and number lined by a single layer of benign mesothelial cells. the disease follows a benign course and is compatible with a normal life expectancy, requiring occasionally partial excision or decompression for relief of pain or other symptoms. malignant potential is exceptional. (from holland et al., cancer medicine, 3d ed, p1345)Mesothelioma, Malignant
a type of mesothelioma with a tendency to metastasize. most tumors originate from either the pleura or peritoneum, tumors may also originate in the pericardium or testicular tissue. it is associated with asbestos exposure. somatic mutations identified in wt1, bcl10, cdkn2a, nf2, and bap1 genes are associated with the malignancy. omim: 156240.Solitary Fibrous Tumor, Pleural
a rare neoplasm, usually benign, derived from mesenchymal fibroblasts located in the submesothelial lining of the pleura. it spite of its various synonyms, it has no features of mesothelial cells and is not related to malignant mesothelioma or asbestos exposure.
Patient EducationClinical
Mesothelioma
The tissue that lines your lungs, stomach, heart, and other organs is called mesothelium. Mesothelioma, also known as malignant mesothelioma, is cancer of that tissue. It usually starts in the lungs, but can also start in the abdomen or other organs.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert C45.2 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About C45.2Overview
What is the ICD-10 code for mesothelioma of pericardium?
The ICD-10-CM code for mesothelioma of pericardium is C45.2 (sometimes written as C452). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is C45.2 (Mesothelioma) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report mesothelioma of pericardium on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does C45.2 group to?
When mesothelioma of pericardium is the principal diagnosis on an inpatient stay, it groups to MS-DRG 314, 315, 316, with relative weights from 0.6821 to 2.0852 depending on complications. Higher weights mean higher Medicare reimbursement.
Is C45.2 a CC or MCC?
CMS lists C45.2 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 2 closely related codes in its exclusion list.
What is the ICD-9 equivalent of C45.2?
Under the General Equivalence Mappings, mesothelioma of pericardium converts to ICD-9-CM 164.1 (malignant neopl heart). The mapping is approximate, so confirm the match fits the documentation.
What HCC is C45.2?
C45.2 (mesothelioma of pericardium) maps to CMS-HCC Category 19 (Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers), commonly written as HCC 19, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 9 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 22.
Does C45.2 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, C45.2 adds a risk adjustment factor of about 1.798 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.957 to 1.989 depending on the payment segment). A more severe related category (HCC 17 and HCC 18) supersedes it when both are reported. See the full factor table on the HCC 19 category page.
