Salivary Gland Tumors: Polarization Colors of PSR Stained Collagen Fibers

Objectives: Salivary gland tumors are a heterogeneous group of neoplasia, characterized histopathologically by different degrees of stromal changes and biologically by different degrees of aggressiveness. The purpose of this study was to investigate the spectrum of polarization colors of collagen fibers stained with picrosirius red (PSR) in benign and malignant tumors of minor salivary glands in order to assess the possible role of this method as a diagnostic tool in controversial and challenging cases. Methods: Ten cases of benign (pleomorphic adenoma, PA), and 20 cases of malignant tumors (10 polymorphous low-grade adenocarcinoma, PLGA and 10 adenoid cystic carcinoma, ACC) as well as 10 cases of mucocele that served as controls were included and stained with PSR. In each case at least 50 thin (0.8 ì) and 50 thick (1.6-2.4 ì) collagen fibers were counted and allocated to polarization colors of green-yellow and yellow-orange. The percent of thin and thick fibers for each color type in each case was calculated. Statistical analysis used one-way ANOVA. Results: Majority of thin fibers (80-90%) were of green-yellow color in all tumors and control cases. No significant differences were found in the distribution of the polarization colors of the collagen fibers among all examined cases (p>0.05). The percent of thick fibers of PA and mucocele of green-yellow color (13% and 12%, respectively) was significantly lower than that of PLGA and ACC (46.4% and 47.5%, respectively) (p=0.001). No significant differences were found in the distribution of the polarization colors of the collagen fibers between PLGA and ACC (p>0.05). Conclusion: The PSR method may help distinguishing benign from malignant salivary gland tumors but not between aggressive (ACC) and less aggressive (PLGA) malignant tumors. The study was supported by the Ed and Herb Chair in Oral Pathology, Tel Aviv University.