Background and purpose: Salivary gland neoplasms are heterogeneous and have low prevalence. Hematoxylin- eosin staining is used for their diagnosis, however, sometimes diagnosis may not be made by this method, so other methods are necessary. The aim of this study was to determine whether morphometry is an appropriate method in differentiating benign and malignant salivary tumors or not.

Materials and methods: A cross-sectional study was done (in Babol Dental School, 2015) in which 60 paraffin embedded blocks of pleomorphic adenoma, adenoid cystic carcinoma, and mucoepidermoid carcinoma were used. Two 5-micron sections were cut for hematoxylin-eosin and methyl green-pyronin staining. Images of stained slides of tumoral components were acquired at 100x magnification on an Olympus BX41, Japan Optical, in three microscopic thin-sections using lgvc camera, Tokyo, Japan which was connected to a computer. An average of 100 nuclei were examined in three microscopic fields. Morphometric and qualitative evaluation of the nucleoli (single- nucleolus and multi-nucleolar) were performed and data analysis was done applying Kruskal-Wallis and Mann-Whitney tests.

Results: The maximum area of nucleus was detected in pleomorphic adenoma and the maximum area of cytoplasm was seen in mucoepidermoid carcinoma. The highest ratio of nuclear to cytoplasmic area and the highest ratio of large to small nuclear diameter were observed in adenoid cystic carcinoma and pleomorphic adenoma, respectively. There were significant differences between three lesions in terms of morphometric characteristics mentioned (P< 0.001).

Conclusion: The results indicated that histomorphometry using methyl green pyronin staining is not useful in differentiating the benign and malignant salivary gland tumors.