The Challenge of Diagnosing Pleural Tuberculosis Infection

Tuberculosis (TB) remains a major threat problem and pleural TB is the most frequent extrapulmonary form of this disease. The diagnosis of TB involvement of the pleura is still challenging since clinical and imagistic findings are extremely non-specific. Clinical findings, chest X-ray, CT scan and simple pleural fluid analysis may be suggestive but do not confirm the diagnosis of pleural TB. Tuberculin skin test is often negative. Identification of the mycobacteria by culture is difficult and the results from sputum and pleural fluid are often negative. Recent advances such as the BACTEC system and the polymerase chain reaction (PCR) have increased the rate of mycobacteria identification. Among the new biomarkers, the most promising are adenosine-deaminase (ADA) and interferon-gamma (IFN-gamma). In certain circumstances, the high levels of ADA and/or IFN-gamma may allow the clinician to start specific TB therapy in the absence of a confirmation by cultures or biopsy. Pleural biopsy (blind percutaneous or through thoracoscopy) remains an option for cases which are not elucidated by less invasive methods.