ICD-10 Code J91.0 – Malignant pleural effusion (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code J91.0 – Malignant pleural effusion
What it is
J91.0 identifies pleural fluid buildup caused by cancer involvement of the pleura or nearby malignancy. Use it when the effusion is documented as malignant or metastatic, not simply present with cancer.
Clinical signs
Common findings include shortness of breath, chest discomfort, cough, and reduced breath sounds on the affected side. Imaging or thoracentesis may support the diagnosis; clinical features vary, refer to documentation.
When to use this code
Use J91.0 when the provider documents malignant pleural effusion, pleural metastasis, or cancer-related pleural fluid. It may be assigned with the underlying malignancy when both conditions are documented and supported.
Choose this code when the effusion is attributed to cancer rather than infection, heart failure, or another nonmalignant cause. Check documentation if the chart only says “pleural effusion” without a malignant link.
Do not use for
Do not use J91.0 for unspecified pleural effusion or effusions from nonmalignant conditions. If the record does not clearly connect the effusion to malignancy, check documentation.
Coding tip
Link the effusion to the cancer in the record before coding J91.0.