Pleural Biopsy Diagnostic Methods

Pleural biopsy is indicated when initial thoracentesis demonstrates an exudate (Light's criteria) without a clear diagnosis, particularly when malignancy or tuberculosis is suspected. Cytology alone has limited sensitivity (60-80% for malignancy, much lower for mesothelioma), making tissue acquisition essential for definitive diagnosis and molecular testing in cancer.

Available methods include: 1) Closed needle biopsy (Abrams, Cope, or Tru-cut needles) — historically first-line, ~50% yield for malignancy and 80% for TB pleuritis when granulomas/AFB present, but blinded technique misses focal disease; 2) Image-guided pleural biopsy (ultrasound or CT-guided) — improves yield to 75-85% by targeting nodular pleural thickening; 3) Medical thoracoscopy (semi-rigid or rigid pleuroscopy under conscious sedation) — diagnostic yield >90% with direct visualization, multiple biopsy capability, and concurrent pleurodesis if indicated; 4) Video-assisted thoracoscopic surgery (VATS) — surgical thoracoscopy under general anesthesia, reserved for failed medical approaches or when extensive intervention needed.

Diagnostic workup of exudates combines pleural fluid analysis (cytology, cell count, biochemistry, microbiology, ADA, IL-2 receptor for TB), serum markers (LDH, protein), imaging (chest CT for pleural thickening pattern, mediastinal lymphadenopathy), and tissue diagnosis. ADA >40 U/L has high sensitivity/specificity for TB in endemic regions. Talc pleurodesis (poudrage) can be performed at thoracoscopy for malignant effusions. Indwelling pleural catheters offer alternative palliation for recurrent malignant effusions.