Argyrophilic nucleolar organizer regions in benign and malignant mesothelial lesions

Georgian Medical News. 2005 Nov;(128):91-3. [Link]

Vacharadze K, Burkadze G, Turashvili G, Kiria N.

National Center of Tuberculosis and Lung diseases, Tbilisi, Georgia.


The aim our study was to assess the usefulness of AgNOR stain in distinguishing between benign and malignant mesothelial lesions. The patients were divided into three groups: group I – reactive mesothelium (71 cases), group II – hyperplastic mesothelium (66 cases), group III – epithelial type mesothelioma (52 cases). Smears were stained by Pap and AgNOR methods. After staining, all cases were randomized for blind evaluation. Each case was viewed independently by two observers. AgNORs were identified as black, usually spheric particles observed within the nucleolus. For each cell, the number of AgNOR-positive cells and the number of AgNOR-dots per nucleus were counted. Our results show that AgNOR staining is useful to differentiate epithelial type mesothelioma and benign mesothelial lesions such as reactive and hyperplastic mesothelium. This differentiation is based primarily on the mean number of AgNOR-dots per cell rather than number of AgNOR-positive cells. AgNOR is highly sensitive, specific and cost-effective technology which can be used as an ancillary diagnostic approach for distinguishing between reactive and/or hyperplastic changes of mesothelium as well as in differential diagnosis of epithelial type mesothelioma.