An evaluation on the importance of phosphotungstic acid haematoxyiin (PTAH) staining in differential diagnosis of salivary gland neoplasms

The differential diagnosis between pleomorphic adenoma, the most common salivary gland neoplasm, microscopically, and two other common salivary gland neoplasms, meaning adenoid cystic carcinoma and mucoepidermoid carcinoma, is difficut.The purpose of this study was to determine the differences between pleomorphic adenoma, adenoid cystic carcinoma and mucoepidermoid carcinoma regarding the staining intensity with PTAH and H&E and also to investigate the relationship between staining intensity with PTAH and malignancy grade in mucoepidermoid carcinoma. 72 paraffin embeded samples including 24 pleomorphic adenoma, 24 adenoid cystic carcinoma and 24 mucoepidermoid carcinoma were selected and stained with PTAH. The staining intensity in total, in nucleus and cytoplasm of tumoral cells were evaluated and compared with H&E staining, statistically. The results were analyzed by Kruskal-Wallis, and Wilcoxon signed ranks tests (P<0.05).The logistic model was presented to predict the degree of malignancies through the assessment of nucleus and cytoplasm staining intensity in tumoral cells, and the patient's age. In this study, a statistically significant relationship was observed between staining intensity by PTAH and H& E in nucleus of tumoral cells in pleomorphic adenoma. Moreover, statistically significant relation between staining intensity by PTAH and H & E in cytoplasm of tumoral cells in adenoid cystic carcinoma was found. But there was no relation in other cases. On the other hand, a statistically significant relation between intensity of staining in total, in nucleus and cytoplasm of tumoral cells and the type of tumor was found. No relation was obtained between malignancy grade of mucoepidermoid carcinoma and staining intensity in total, in nucleus and cytoplasm of tumoral cells. The presented logistic model indicated a direct relation between tumor malignancy with patient's age and staining intensity in nucleus of tumoral cells, but a reverse relation was found between cytoplasm staining intensity in tumoral cells and tumor malignancy.Our findings show that PTAH and H & E staining methods, lead to similar results, however, PTAH staining is a reliable method in differential diagnosis of such salivary gland tumors.