Diagnosis of pleural effusions by chromosome analysis.

Cytogenetic changes, namely numerical (aneuploidy) and morphologic chromosome abnormalities including markers, clearly indicate the presence of malignant cells. To compare the utility of chromosome and cytogenetic analysis, the idiopathic pleural effusions of 60 patients were subjected to a double-blind analysis. A fluid was considered "positive" for malignancy if there was a marker chromosome, or if 10 percent of metaphases were hyperdiploid. Of the 33 neoplastic effusion, 30 (91 percent) were diagnosed "positive" by chromosome analysis whereas only 21 (64 percent) were classified "positive" or "suggestive positive" by cytology. All 27 benign effusions were correctly diagnosed by cytology; however, two were labelled "positive" by chromosome analysis. Combining the results of cytologic and chromosome analysis did not increase the number of "positive" diagnoses.