Argyrophilic nucleolar organizer region (AgNOR) technique: a helpful tool for differential diagnosis in urinary cytology

The aim of this study was to investigate whether the AgNOR technique could be helpful for the cytologic diagnosis of neoplastic and non-neoplastic uri nary tract lesions. We analysed the AgNOR pattern in urinary cytology in sa mples from 70 patients. In every case the average number of silver precipit ations per nucleus was counted and the range between the minimum and maximu m AgNOR value calculated. Furthermore we noted whether the AgNOR precipitat ions had a homogeneous or heterogeneous distribution. The diseases were cla ssified in three groups. non-neoplastic lesions, low grade and high grade c arcinoma. Linear discriminant analysis (with jack-knife procedure) was perf ormed with the AgNOR parameters as independent variables. The final diagnos is of each patient had been established by histological analysis of bladder biopsies. We obtained a correct classification in 84.3% of the cases. All patients with normal or reactive lesions were correctly classified and only two cases of low grade malignancy were erroneously diagnosed as non-malign ant. Five high grade neoplasms had been classified as low grade and four lo w grade carcinomas had been over-diagnosed as high grade neoplasms. We conc lude that a combined qualitative and quantitative AgNOR analysis can be use ful in the differential diagnosis of urinary cytology.