Sonographic septation in lymphocyte-rich exudative pleural effusions - A useful diagnostic predictor for tuberculosis

Objective. The purpose of this study was to evaluate the role of the sonographic features of lymphocyte-rich exudative pleural effusions in the differential diagnosis of tuberculosis and lung cancer in an area with a high incidence of tuberculosis. Methods. Medical records of patients undergoing chest sonography between January 2003 and June 2005 (30 months) were reviewed retrospectively. The enrolled patients included 73 with lung cancer-related pleural effusions and 93 with tuberculous pleural effusions. The sonographic appearances of the pleural effusions were defined in terms of 4 patterns; anechoic, homogeneously echogenic, complex septated, and complex nonseptated. Results. Among the 73 lung cancer-related pleural effusions, there were sonographic appearances of an anechoic pattern in 11% (8/73), a complex septated pattern in 4% (3/73), and a complex nonseptated pattern in 85% (62/73). In 93 tuberculous pleural effusions, there were sonographic appearances of an anechoic pattern in 12% (11/93), a complex septated pattern in 47% (44/93), and a complex nonseptated pattern in 41% (38/93). Apparently, a complex septated pattern in the sonographic appearance of lymphocyte-rich pleural effusions is a useful diagnostic predictor for differentiating tuberculosis from lung cancer (95% confidence interval, -0.57 to -0.29). If we define the complex septated pattern in the sonographic appearance of lymphocyte-rich exudative pleural effusions as a predictor for tuberculous pleural effusions, we can achieve sensitivity, specificity, positive predictive value, negative A predictive value, and positive likelihood ratio values of 47%, 96%, 94%, 59%, and 12, respectively. A Conclusions. A complex septated pattern in the sonographic appearance is a useful predictor of tuberculosis in lymphocyte-rich exudative pleural effusions.