Tuberculous Pleural Effusion

Tuberculous pleural effusion is a delayed hypersensitivity response to mycobacterial antigens in the pleural space, often with few bacilli, and is the commonest form of pleural tuberculosis. It is the leading cause of lymphocytic exudate in high prevalence settings.

• Typical in young adults and in HIV positive patients (where sputum may also be positive).
• Without treatment, effusion resolves spontaneously but about half develop active tuberculosis within 5 years.

Pleuritic chest pain, fever, dry cough and progressive dyspnoea over days to weeks, with night sweats and weight loss.

• Dullness to percussion, reduced breath sounds and vocal resonance on the affected side; usually unilateral and moderate in size.
• Differential diagnosis: parapneumonic effusion and empyema, malignant effusion, heart failure, pulmonary embolism, cirrhosis, nephrotic syndrome, connective tissue disease, sarcoidosis, rheumatoid pleurisy, lymphoma, chylothorax, haemothorax, pancreatitis.
• Complications: pleural thickening and fibrothorax, empyema, bronchopleural fistula, residual restriction, persistent loculation, dissemination.

Diagnostic thoracentesis is the key investigation.

• Pleural fluid: exudate (protein over 30 g/L or fluid to serum protein ratio over 0.5, LDH over two thirds of upper limit of serum), lymphocyte predominance, adenosine deaminase over 40 U/L, low mesothelial cells; Xpert MTB/RIF Ultra and culture (low yield; culture positive in under 30 percent).
• Pleural biopsy (image guided, thoracoscopic or closed needle) showing caseating granuloma gives high diagnostic yield.
• Sputum Xpert and chest radiograph or ultrasound; HIV test and CD4; urine lipoarabinomannan.

Full antituberculous therapy with drainage for symptomatic relief.

• Supportive: rest, analgesia (paracetamol 1 g four times daily, ibuprofen 400 mg three times daily), nutrition, oxygen for hypoxia, breathing exercises and physiotherapy to prevent fibrosis.
• Pharmacological: 2 months of isoniazid, rifampicin, pyrazinamide and ethambutol followed by 4 months of isoniazid and rifampicin (daily doses isoniazid 5 mg/kg, rifampicin 10 mg/kg, pyrazinamide 25 mg/kg, ethambutol 15 mg/kg). Pyridoxine 25 to 50 mg daily. Corticosteroids are not routinely given; prednisolone 0.75 to 1 mg/kg for 2 to 6 weeks may be used for severe pleuritic symptoms. HIV: antiretroviral therapy within 2 to 8 weeks; dolutegravir 50 mg twice daily during rifampicin.
• Procedures: therapeutic thoracentesis (not over 1.5 L at one time) for breathlessness; intercostal chest drain for large, loculated or purulent effusion; intrapleural fibrinolysis (alteplase) or surgical decortication for empyema or entrapped lung.
• Special groups: pregnancy, first line regimen with pyridoxine; children, weight band dosing; HIV, parallel search for disseminated disease; elderly, rule out malignancy.
• Red flags: purulent fluid, large effusion causing hypoxia, bloody effusion, bilateral effusions, no response in 2 weeks, weight loss with haemoptysis.
• Follow-up: clinical review at 2 weeks and monthly; chest radiograph at 2 and 6 months; spirometry if residual pleural thickening.