ICD-10 Code C45 – Mesothelioma (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C45 – Mesothelioma
What it is
C45 identifies mesothelioma, a malignant tumor that arises from the mesothelial lining of the pleura, peritoneum, pericardium, or tunica vaginalis. Use it when documentation clearly states mesothelioma.
Clinical signs
Clinical features vary by site. Pleural disease may present with chest pain, dyspnea, or pleural effusion; peritoneal involvement may cause abdominal distention or pain. Check documentation for the confirmed site.
When to use this code
Use C45 when the provider documents mesothelioma as the confirmed diagnosis, including cases with pathology or specialist confirmation. Code the documented anatomic site when available, because site-specific detail may affect final code selection. If the record only says “suspected” or “rule out,” do not assign this code.
Do not use for
Do not use C45 for benign pleural disease, other pleural tumors, or nonspecific asbestos exposure without a documented malignancy. If the diagnosis is uncertain, check documentation.
Coding tip
Review the pathology and final provider assessment to confirm both malignancy and site before coding.