differentiation between benign, reactive and malignant cells in serosal body fluids by agnor staining

argyrophilic nucleolar organizer regions (agnors) were determined in 94 pleural, pericardial and peritoneal effusions. the results were correlated with cytologic diagnosis to determine the diagnostic potential of this technique. cytologically the number of normal, reactive and malignant effusions were 32, 28 and 34 respectively. the mean agnor counts for normal, reactive and malignant specimens were 1.365,2.328 and 4.747 respectively. the cut-off points between normal-reactive and reactive-malignant specimens were 1.84 and 3.53 respectively. all of the malignant specimens (100%) had agnor counts above 3.53. neither reactive nor normal specimens had agnor counts above 3.53. 82.1 % of reactive specimens had agnor counts above 1.84 and 87.5% of normal specimens had agnor counts below this point. there was a statistically significant difference between the agnor counts in normal, reactive and malignant effusions (p<0.001). we conclude that the agnor method is a specific diagnostic tool for serosal cavity effusions, especially when malignancy is suspected.