RESUMEN
A prospective study of 76 consecutive patients over the age of 40 years, with exudative pleural effusion, was undertaken to determine the common causes of such a clinical condition. Malignant pleural effusions were the most common in this series, found in 49 patients (64.47%), all but one being metastatic from elsewhere. Forty were secondary to a carcinoma of the bronchus, 3 from carcinoma of the breast, 1 each from carcinoma of the ovary, oesophagus, and larynx; lymphoma accounted for the remaining 2. Infective causes accounted for 24 of the effusions (31.57%). Of the infections, tuberculosis was the most common, accounting for 17 of the 24. Other infective causes included bacterial empyemas in 4, ruptured amoebic liver abscess in 2, and actinomycosis in 1. Pancreatitis, pulmonary thromboembolism, and a post-cardiotomy syndrome were diagnosed in 1 patient each, while the diagnosis remained unknown in the remaining 5 patients. In 2 patients the diagnosis was made on autopsy.