STATE OF THE ART REVIEW Tuberculous Pleural Effusion Jose ´ M. Porcel Received: 19 February 2009 / Accepted: 26 July 2009 / Published online: 13 August 2009 Ó Springer Science+Business Media, LLC 2009 Abstract Tuberculous pleural effusion is one of the most common forms of extrapulmonary tuberculosis (TB). The immediate cause of the effusion is a delayed hypersensi- tivity response to mycobacterial antigens in the pleural space. For this reason microbiological analyses are often negative and limited by the lengthy delay in obtaining results. In areas with high TB prevalence, pleural fluid adenosine deaminase (ADA) levels greater than 40 U/l argue strongly for TB; in contrast, low levels of pleural ADA have high negative predictive value in low-preva- lence countries. The specificity of this enzyme increases if only lymphocytic exudates are considered. The shortcom- ing of the ADA test is its inability to provide culture and drug sensitivity information, which is paramount in coun- tries with a high degree of resistance to anti-TB drugs. Sputum induction (in addition to pleural fluid) for acid-fast bacilli and culture is a recommended procedure in all patients with TB pleurisy. The microscopic-observation drug-susceptibility assay performed on pleural fluid or pleural tissue increases by two to three times the detection of TB over conventional cultures, and it allows for the identification of multidrug-resistant TB. A reasonable management strategy for pleural TB would be to initiate a four-drug regimen and perform a therapeutic thoracentesis in patients with large, symptomatic effusions. Keywords Pleural effusion Á Tuberculosis Á Adenosine deaminase Introduction Tuberculosis (TB) is a major public health problem in developing countries. There were an estimated 9.2 million new cases of TB in 2006, of which 8% were in human immunodeficiency virus (HIV)-positive patients [1]. In that year, the overall annual incidence of TB in Europe was reported to be 49 cases per 100,000 people, ranging from 2 to 141 cases depending on the country (e.g., Spain 30/ 100,000). These figures were 4.6/100,000 people in the United States and 363/100,000 people in Africa. The country with the highest TB incidence rate was Swaziland (southern Africa), with 1,155 cases/100,000 people; that with the lowest was Monaco (Europe), with 2/100,000 [1]. Overall, the African, southeast Asian, and western Pacific regions account for more than 80% of the total case noti- fications of TB in the world. In developed nations like the United States, TB is primarily a disease of immigrants from high-prevalence countries (who comprise over half of all reported TB cases) as well as the socially and eco- nomically disadvantaged. Although pulmonary disease is the most common form of TB, extrapulmonary TB affecting mainly the lymph nodes and pleura serves as the initial presentation in about 25% of adults. Pleural TB accounts for 4% of all TB cases in the United States [2]; in Spain, however, this percentage is greater than 10% [3]. TB is one of the most common causes of pleural effusion in some geographical areas [4]. At the author’s institution, the leading etiologies of pleural effusion in the 2000 patients who underwent diagnostic thoracentesis during the last 12 years were cancer (30%), J. M. Porcel (&) Department of Internal Medicine, Pleural Diseases Unit, Arnau de Vilanova University Hospital, Institut de Recerca Biome `dica de Lleida (IRBLLEIDA), Avda Alcalde Rovira Roure 80, 25198 Lleida, Spain e-mail: jporcelp@yahoo.es 123 Lung (2009) 187:263–270 DOI 10.1007/s00408-009-9165-3