Usefulness AgNOR assay in the assessment of serous effusions

Background: AgNOR technique detects, using silver salts, argyrophylic prote ins of the nucleolar organizer region (NOR). The number and size of NOR ref lect cell activity, proliferation and transformation and may help to differ entiate benign from malignant cells. Aim: To asses the value of AgNOR assay to differentiate reactive mesothelial cells from malignant cells in serous effusions. Material and methods: Thirty one fluids obtained from 16 pleura l , 14 peritoneal and one pericardial effusion, were studied. The fluids we re processed with Giemsa and Papanicolau stains and with the AgNOR techniqu e. The number of AgNOR dots were counted (only when it was possible to dist inguish each individual dot) and the mean value per nucleus was calculated for each smear. Results: Mesothelial cells had a mean of 4,88 +/- 1,5 dots compared with 13,78 +/- 3,88 dots in the malignant cells (p < 0.001). Concl usions: AgNOR assay can be useful for the differentiation of benign and mal ignant cells in serous effusions.