What causes malignant pleural effusion?

The pleura are thin layers around the lungs and inside the chest wall. A small amount of fluid normally helps these layers move smoothly. Cancer cells may reach the pleura, make the lining inflamed, or obstruct lymphatic drainage. The resulting fluid can press on the lung and limit its expansion.

Lung cancer, breast cancer, and mesothelioma can cause this problem. A pleural effusion is not automatically malignant: infection, heart problems, inflammation, or other illnesses can also produce fluid. A sample is often examined to clarify its cause.

Report breathlessness, chest heaviness, a dry cough, or pain that worsens with a deep breath to your care team. Assessment may include listening to the chest, imaging, and a procedure that removes fluid for testing. Drainage can relieve pressure, while treatment directed at the cancer or pleura may reduce recurrence.

Rest upright if that makes breathing easier, and use prescribed medicines exactly as directed. Do not assume worsening breathlessness is only the known effusion; infection, a clot, or another urgent problem can cause similar symptoms.

Get urgent medical help for sudden or severe breathlessness, blue lips, confusion, fainting, severe chest pain, or coughing blood. Contact your team promptly if breathing becomes harder, fever develops, or symptoms return after a drainage procedure.

Ask whether the fluid needs sampling, which cancer or non-cancer cause is suspected, when drainage is useful, how recurrence will be managed, and which breathing changes require urgent help.