What is ICD-10 code C45.0?

C45.0 is the ICD-10-CM diagnosis code for Mesothelioma of pleura. A rare and aggressive cancer that develops in the thin layer of tissue covering the lungs (pleura), usually caused by asbestos exposure. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C45.0 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C45.0 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. C45.0 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. C45.0 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for C45.0?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For C45.0, V28 maps to Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers at RAF 1.798 while V24 mapped to Lung and Other Severe Cancers at RAF 1.024. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting C45.0?

Document any history of asbestos exposure in the patient record, as this is relevant for etiology and potential workers' compensation claims Mesothelioma of pleura is the most common type; ensure you are not confusing this with lung cancer or other thoracic malignancies Because C45.0 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

2026 ICD-10-CM C45.0: Mesothelioma of pleura

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Code lookupC45.0Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of mesothelial and soft tissue (C45-C49)

C45.0

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Mesothelioma of pleura

A rare and aggressive cancer that develops in the thin layer of tissue covering the lungs (pleura), usually caused by asbestos exposure.

Buddy Insight

Mesothelioma of the pleura is a highly aggressive cancer of the pleural lining, almost exclusively caused by asbestos exposure with a latency period of 20-50 years.

CMS-HCC V28

Mapped

HCC 19

Myelodysplastic Syndromes, Mu...

RAF 1.798

CMS-HCC V24

Mapped

HCC 9

Lung and Other Severe Cancers

RAF 1.024

ACA/HHS

Mapped

HCC 9

HHS-HCC 9

Varies by metal level

ESRD/PACE

Mapped

HCC 9

Lung and Other Severe Cancers

RAF 0.181

RXHCC

Mapped

HCC 22

Cancer, Other Specified Sites

RAF 0.124

Code Book Path

Official

C45Mesothelioma

C45.0Mesothelioma of pleura

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for C45.0 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for C45.0 in this effective period.

Related Child Codes

Official

C45.1Mesothelioma of peritoneum

C45.2Mesothelioma of pericardium

C45.7Mesothelioma of other sites

C45.9Mesothelioma, unspecified

Includes

Official

ICD-10-CM does not list Includes notes for C45.0 in this effective period.

Excludes 1

Official

other malignant neoplasm of pleura (C38.4)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for C45.0 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for C45.0 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for C45.0 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Histologic confirmation of mesothelioma (epithelioid, sarcomatoid, or biphasic subtype)

Asbestos exposure history

Laterality of pleural involvement (right vs. left, or bilateral)

Staging by International Mesothelioma Interest Group or AJCC criteria

MEAT Support

HCC Buddy guidance

Histologic confirmation of mesothelioma (epithelioid, sarcomatoid, or biphasic subtype)

Asbestos exposure history

Laterality of pleural involvement (right vs. left, or bilateral)

Staging by International Mesothelioma Interest Group or AJCC criteria

Audit Caution

HCC Buddy guidance

Confusing pleural mesothelioma with lung cancer — these are fundamentally different diseases requiring different staging, treatment, and coding

Coding metastatic pleural disease (C78.2) as mesothelioma — pleural metastases from lung or breast cancer are far more common

Using C38.4 (malignant neoplasm of pleura) instead of C45.0 for mesothelioma — mesothelioma has its own specific code

Not confirming the diagnosis histologically — mesothelioma requires specialized immunohistochemistry to confirm

Common Mistakes

HCC Buddy guidance

C34.x — Malignant neoplasm of lung (bronchus); lung cancer is parenchymal, mesothelioma is pleural — different diseases with different treatments

C38.4 — Malignant neoplasm of pleura; used for non-mesothelioma pleural cancers

C78.2 — Secondary malignant neoplasm of pleura; for metastatic disease to the pleura from other cancers

C45.1 — Mesothelioma of peritoneum; different serosal surface

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is C45.0 an HCC code?

Yes. C45.0 (Mesothelioma of pleura) maps to Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers under the CMS-HCC V28 risk adjustment model (and Lung and Other Severe Cancers under V24), with a community non-dual aged RAF of 1.798. It is billable for payment year 2026.

Coder answer: C45.0 is billable and maps to V28 HCC 19, Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: C45.0
Description: Mesothelioma of pleura
HCC (V28): HCC 19 — Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers
RAF: 1.798
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 19, Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers

1.798

V24HCC 9, Lung and Other Severe Cancers

1.024

ESRDHCC 9, Lung and Other Severe Cancers

0.181

RxHCCHCC 22, Cancer, Other Specified Sites

0.124

Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

Work C45.0 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for C45.0

For C45.0to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed C45.0 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

C45.0 is the ICD-10-CM diagnosis code for mesothelioma of pleura. A rare and aggressive cancer that develops in the thin layer of tissue covering the lungs (pleura), usually caused by asbestos exposure. C45.0 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of mesothelial and soft tissue (c45-c49).

Under the CMS-HCC V28 risk adjustment model, C45.0 maps to Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers (HCC 19) with a community, non-dual, aged base RAF weight of 1.798. Under the older CMS-HCC V24 model, C45.0 maps to Lung and Other Severe Cancers (HCC 9) with a community, non-dual, aged base RAF weight of 1.024. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

Document any history of asbestos exposure in the patient record, as this is relevant for etiology and potential workers' compensation claims. Because C45.0 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for C45.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Document any history of asbestos exposure in the patient record, as this is relevant for etiology and potential workers' compensation claims
•Mesothelioma of pleura is the most common type; ensure you are not confusing this with lung cancer or other thoracic malignancies

Clinical Significance

Mesothelioma of the pleura is a highly aggressive cancer of the pleural lining, almost exclusively caused by asbestos exposure with a latency period of 20-50 years. Median survival is 12-18 months. This cancer carries one of the highest RAF weights in V24, reflecting its severity and resource intensity. Accurate coding requires distinguishing it from metastatic pleural disease.

Documentation Requirements

✓Histologic confirmation of mesothelioma (epithelioid, sarcomatoid, or biphasic subtype)
✓Asbestos exposure history
✓Laterality of pleural involvement (right vs. left, or bilateral)
✓Staging by International Mesothelioma Interest Group or AJCC criteria
✓Treatment plan (extrapleural pneumonectomy, pleurectomy/decortication, chemotherapy, immunotherapy)
✓Performance status and prognosis documentation

Excludes 1, Do NOT code together

other malignant neoplasm of pleura (C38.4)

Commonly Confused Codes

•C34.x: Malignant neoplasm of lung (bronchus); lung cancer is parenchymal, mesothelioma is pleural: different diseases with different treatments
•C38.4: Malignant neoplasm of pleura; used for non-mesothelioma pleural cancers
•C78.2: Secondary malignant neoplasm of pleura; for metastatic disease to the pleura from other cancers
•C45.1: Mesothelioma of peritoneum; different serosal surface