Interphase nucleolar organizer regions in the evaluation of serosal cavity effusions

Argyrophilic nucleolar organizer regions (AgNORs) were determined in 38 pleural and peritoneal effusions from patients with malignant solid tumors. The results were correlated with the cytologic diagnosis and flow cytometric DNA analysis to determine the diagnostic potential of this technique. Cytologically, 13 effusions were benign, 23 malignant and 2 indeterminate (5.2%). The mean AgNOR counts for benign, malignant and indeterminate specimens were 2.99, 3.94 and 3.50, respectively. Low AgNOR counts (< 4.0) were obtained in 12 (90.9%) of the 13 benign, 16 (60.0%) of the 23 malignant and 1 of the indeterminate effusions. High AgNOR counts (> 4.0) were noted in 1 (9.1%) of the benign, 7 (35.0%) of the malignant and 1 (5.0%) of the indeterminate specimens. There was no statistically significant difference between the AgNOR count in benign and malignant effusions (P = .48). All 10 benign effusions analyzed with flow cytometry were DNA diploid. Seven (35.0%) of the 20 cytologically malignant effusions were DNA aneuploid, and 13 (70.0%) were DNA diploid. Proliferative activity was low (< 7.0%) in 23 cases and high (> 7.0%) in 7 (6 malignant and 1 benign). There was no statistical correlation between the AgNOR count and DNA ploidy (P = .11) or proliferative activity (P = .23). We conclude that the AgNOR method lacks sensitivity as a diagnostic tool for serosal cavity effusions.