[Usefulness of computerized tomography in the study of pleural effusion with no presumed diagnosis].

To establish the diagnostic yield of computerized tomography (CT) in pleural effusions with no presumed diagnosis arising from standard clinical examination. A prospective protocol study enrolling all cases of effusion admitted to our hospital between January 1994 through July 1995 without a presumed diagnosis after initial testing that included thoracocentesis. Twenty-two patients were enrolled. All were given a CT scan as well as other complementary examinations considered appropriate and were referred to our outpatient clinic for follow-up. The CT images were read by an expert radiologist and their contribution was classified as "diagnostic", "suggestive" or "nil". A definitive etiologic diagnosis was achieved in 14 cases (8 neoplasms, 4 benign due to asbestos, 1 tuberculosis and 1 pulmonary embolism). The CT contribution was nil in 13 cases (59%), "diagnostic" in 6 (2 mesotheliomas, 1 hypernephroma, 1 lymphoma, 1 adenocarcinoma of the colon and another of the ovary) and "suggestive" in 3 (2 benign due to asbestos and 1 lymphoma). Positive information was obtained in 9 cases (41%). CT gives good yield in the investigation of pleural effusions with no presumed diagnosis and should be made available to this group of patients before other more invasive procedures are resorted to. It is especially useful for detecting neoplastic disease of the upper abdomen, mesothelioma and sings of unsuspected exposure to asbestos.