Silver staining efficiency in differential diagnosis of adenoid cystic carcinoma (ACC) from polymorpheus low-grade adenocarcinoma (PLGA)

Objectives The aim of this study is finding a practical and easy way to differentiate, between two malignant tumors Adenoid Cystic Carcinoma (ACC) and Polymorphous Low-grade Adeno Carcinoma (PLGA) histologically. In this regard, We proposed silver nitrate staining (AgNOR). Methods In this cross-sectional study, 30 parrafin-embedded blocks of ACC and 9 paraffin-embedded blocks of PLGA with the most acceptable standards elected and stained with silver nitrate. Then the number and quality (size and pattern) of the stained spots in 5 random microscopic fields at 100× magnification (at least 100 cells) were evaluated. To compare the number of dots between the two tumors T-test was used and the quality of dots, compared with Mann-Whitney U test. Results The mean AgNOR counts for ACC (3/45), and for PLGA (2/45). Significant differences were observed in the number of dots between the ACC and PLGA (p=0.004), but in terms of quality, there was no statistically significant difference between the two tumors. Conclusion AgNOR count can be useful as an available method in confirm the diagnosis of ACC from PLGA.