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 non-septated 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 predictive value, and positive likelihood ratio values of 47%, 96%, 94%, 59%, and 12, respectively.

CONCLUSIONS: A complex septated pattern in the sonographic appearance is a useful predictor of tuberculosis in lymphocyte-rich exudative pleural effusions.