Malignant pleural effusion

This code represents the accumulation of fluid in the pleural space (the area between the lungs and the chest wall) that is caused by the presence of malignant cells. This effusion is a common complication of various cancers, indicating metastatic spread to the pleura or direct tumor invasion.

Use this code when documentation clearly states a pleural effusion is malignant, often confirmed by cytology of the pleural fluid or biopsy of the pleura. This diagnosis is frequently seen in patients with primary lung cancer, breast cancer, lymphoma, or other metastatic malignancies.

• Always code the underlying primary malignancy first, followed by this code as a manifestation.
• Ensure documentation specifies "malignant" effusion; otherwise, a non-malignant effusion code should be used.
• Do not use this code if the effusion is due to a benign condition, even in a cancer patient.