Material and Methods
Between January 1989 and February 1990, 283 patients were idmitted to our hospitals with pleural effusions. Thirty cases were excluded from the present study because either no possible cause vas definitely diagnosed, or more than one was present. The emaining 253 cases were classified on the basis of their diagnosis n the following four groups (Table 1).
Transudates
This group comprised 65 patients (34 men and 31 women) aged fl±9.4 years. In 57 cases, congestive cardiac insufficiency was diagnosed on the basis of compatible clinical and radiologic findings, the disappearance of the effusion after suitable treatment, the absence of pulmonary infiltrates, and nonmalignancy. In other cases, transudates were caused by nephrotic syndromes (three cases), hypoalbuminemia (three cases), or hepatic cirrhosis (two cases).
Neoplastic Exudates
Sixty-seven patients (40 men and 27 women) aged 66 ± 13.7 years had neoplastic tissue in the pleural cavity.

Tuberculous Exudates
In 65 patients (43 men and 22 women) aged 37 ± 19 years, pleural effusion was blamed on tuberculosis, which was diagnosed by identifying the bacillus in pleural liquid and/or biopsy specimen cultures or from the presence of caseous granulomas in pleural biopsy tissue.

Table 1—Etiology of Pleural Effusions