Modified method of AgNOR staining for tissue and interpretation in histopathology

This study was conducted in the department of Pathology King Edward Medical University, from June to December 2002 to introduce the new method of AgNOR staining and its interpretation to increase its reliability. A total of 60 brain specimens were stained with modified AgNOR technique. The diagnosis of malignancy was made on H & E staining. AgNOR counts, variation in size and dispersion of AgNOR dots in cells were graded and compared in malignant and non-malignant lesions. Modified method of AgNOR staining and interpretation was an easy, reliable and reproducible alternative to traditional AgNOR techniques for evaluating proliferation activity of cells in malignant and benign brain lesions. mAgNOR counts of different grades of astrocytoma (2.97 +/- 0.96, 3.97 +/- 0.43, 6.01 +/- 2.74 and 8.01 +/- 3.56) were significantly (P < 0.01) greater when compared with counts of normal brain (0.40 +/- 0.01), and reactive gliosis (0.60 +/- 0.01). AgNOR size and dispersion were of higher grade in a significantly greater proportion of malignancy when compared with benign conditions (P < 0.05). The AgNOR dots were brighter and more clear with modified staining when compared with previous studies. We conclude that modified AgNOR staining technique is simple, quick and reliable to evaluate cell proliferation by detecting AgNORs size and dispersion. In future, AgNOR size and dispersion should be considered rather than the count only. We recommend the use of morphometry for AgNOR size in future. We also recommend the use of modified AgNOR staining for obtaining sound and confidant results in routine paraffin sections.