Causes of Recurrent Pleural Effusion
Malignancy is the most common cause of recurrent pleural effusion requiring intervention, with lung cancer, breast cancer, and lymphoma accounting for the majority of cases, followed by parapneumonic effusions and tuberculosis. 1, 2
Primary Etiologies of Recurrent Effusion
Malignant Effusions
- Lung cancer is the most common malignancy causing pleural effusion, followed by breast cancer and lymphoma, collectively accounting for 26% of all pleural effusions 3, 4
- Malignant effusions have a near 100% recurrence rate at 1 month after simple aspiration alone, making them the predominant cause requiring definitive management 1, 2
- Breast cancer demonstrates bilateral involvement in 10% of cases with unilateral primary tumors, with 50% ipsilateral and 40% contralateral 3
- Lymphoma accounts for approximately 7-10% of malignant effusions, with Hodgkin's disease typically causing obstruction of lymphatic drainage and non-Hodgkin's lymphoma causing direct pleural infiltration 1, 3
- Kaposi's sarcoma represents one-third of pleural effusions in HIV-infected patients 1
Infectious Causes
- Parapneumonic effusions (complicated by infection) represent 28% of effusions in certain populations and require urgent drainage when pH <7.2 1, 4
- Tuberculosis accounts for 14% of effusions in HIV-infected patients and should be reconsidered in persistently undiagnosed cases, particularly with lymphocyte-predominant exudates and positive tuberculin skin tests 1
- Empyemas require antibiotics and intercostal drainage, with surgery needed in selected refractory cases 5
Cardiac and Systemic Causes
- Heart failure is the leading cause of bilateral effusions, accounting for more than 80% of transudative effusions 3, 4
- These effusions typically recur with decompensation and respond to treatment of the underlying cardiac condition 4
Connective Tissue Diseases
- Rheumatoid arthritis causes pleural involvement in 5% of patients, predominantly in men, with glucose levels >1.6 mmol/L (29 mg/dL) essentially excluding this diagnosis 1
- Systemic lupus erythematosus (SLE) causes pleural disease in up to 50% of patients during their disease course, with LE cells in pleural fluid being diagnostic 1
Other Causes
- Pulmonary embolism should be reconsidered in persistently undiagnosed effusions, as there are no specific pleural fluid tests and imaging is required for diagnosis 1
- Cirrhosis and kidney failure cause transudative effusions that may recur with disease progression 4
- Chylothorax represents a less common but important cause requiring specific management 6
Critical Diagnostic Pitfall
In 15% of cases, the cause remains undiagnosed after repeated cytology and pleural biopsy, with many eventually proving to be malignancy upon sustained observation. 1 When effusions remain undiagnosed, tuberculosis and pulmonary embolism must be actively reconsidered since these are amenable to specific treatment 1. Thoracoscopy is advised if malignancy is suspected after routine tests fail 1.
Management Implications for Recurrence
- Intercostal tube drainage without pleurodesis is never recommended due to recurrence rates approaching 100% at 1 month, similar to aspiration alone but with added procedural risk 1, 2, 7
- For malignant effusions with expandable lung, either indwelling pleural catheter or chemical pleurodesis should be used as first-line definitive therapy 2
- For non-expandable lung (trapped lung), indwelling pleural catheter is preferred over pleurodesis attempts 2
- Patients with very short life expectancy (<1 month) should receive repeated therapeutic thoracentesis for palliation rather than definitive procedures 1, 2