C45.0
BillableMesothelioma of pleura
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C45.0 an HCC code?
Yes. C45.0 maps to Lymphoma and Other Cancers under the CMS-HCC V28 risk adjustment model (and Lung and Other Severe Cancers under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. 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.
MEAT Criteria for C45.0
For C45.0 to 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.
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 Lymphoma and Other Cancers (HCC 19) with a community, non-dual, aged base RAF weight of 0.105. 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 0.973. 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