From the Guidelines
Pleural effusion is caused by over 60 recognized causes, including disease local to the pleura or underlying lung, systemic conditions, organ dysfunction, and drugs, which lead to an imbalance between fluid production and absorption in the pleural space. The causes of pleural effusion can be broadly categorized into:
- Disease local to the pleura or underlying lung
- Systemic conditions
- Organ dysfunction
- Drugs, with tyrosine kinase inhibitors being the most common drug implicated in causing exudative pleural effusions 1 Some of the common causes include heart failure, pneumonia, malignancies, pulmonary embolism, tuberculosis, cirrhosis with ascites, connective tissue diseases, pancreatitis, and medication reactions. Determining the underlying cause is essential for proper treatment, which may involve treating the primary condition, draining the fluid through thoracentesis, or addressing inflammation with medications, as outlined in the British Thoracic Society guideline for pleural disease 1. A careful history and physical examination of the patient, including a detailed occupational history and drug history, remains the most important first step when evaluating someone with an undiagnosed pleural effusion, and thoracic ultrasound (TUS) should be performed on every patient at their initial presentation 1.
From the Research
Causes of Pleural Effusion
The causes of pleural effusion can be varied and include:
- Systemic conditions
- Inflammatory conditions
- Infectious conditions
- Malignant conditions 2 Specifically, the most common causes of pleural effusion are:
- Congestive heart failure
- Cancer, with lung and breast cancer being the most common causes of malignant pleural effusions 3, 4, 5
- Pneumonia
- Pulmonary embolism 5
- Tuberculosis, with the presence of certain markers such as adenosine deaminase (ADA) and CXCL10 being indicative of tuberculous pleural effusions 2, 6
Malignant Pleural Effusions
Malignant pleural effusions are a common complication of cancer, with most cases being secondary to metastases to the pleura from lung or breast cancer 3, 4. The presence of a malignant pleural effusion indicates advanced disease and poor survival, with the cancer being upstaged to stage 4 in the case of lung cancer 4.
Diagnostic Approach
The diagnostic approach to pleural effusions involves a combination of medical history, physical examination, imaging tests, and pleural fluid analyses, including specific biomarkers such as natriuretic peptides for heart failure, adenosine deaminase for tuberculosis, and mesothelin for mesothelioma 2. In some cases, invasive procedures such as pleuroscopic biopsies or image-guided biopsies may be required to establish a diagnosis 2, 5.