Diagnosis of pleural effusions. Experience with clinical studies, 1986 to 1990

OBJECTIVES: To identify in patients with pleural effusion which procedures are most useful in separating malignant from nonmalignant pleural effusions and to identify which procedures most commonly lead to a definitive diagnosis. DESIGN: Prospective consecutive case series. SETTING: Pulmonary referral hospital in Prague, Czech Republic. PATIENTS: One hundred seventy-one adults between ages 18 and 70 years with a pleural effusion and a Karnofsky score of 70 or above. INTERVENTIONS: All patients underwent history, physical, pleural fluid cytologic study, laboratory evaluation of serum and pleural fluid, pleural biopsy, bronchoscopy, and lung scan and/or pulmonary arteriogram. RESULTS: In this series in which 45% of the patients had malignant effusions, 19% had paramalignant effusions, and 36% had benign diseases, the pleural fluid cytologic study was the best for establishing a diagnosis. The pleural fluid carcinoembryonic antigen (CEA) levels above 10 had a high specificity (90%) for malignancy but had low sensitivity (37%). The pleural fluid CEA level was increased only in 19% of patients with paramalignant effusions. Although there were statistically significant differences in the mean results on several biochemical tests of pleural fluid, none were very accurate in separating malignant from benign disease. CONCLUSION: From this study, we conclude that patients with an undiagnosed pleural effusion should be evaluated in an individualized stepwise manner. If malignancy is strongly considered, the initial three steps should be relatively noninvasive and include clinical evaluation and cytologic study.