Characterization of vascular density and collagenous matrix in oral pleomorphic adenomas.

Background: Tumor vascular density and collagen matrix organization are critical factors to neoplasia development and progression. This study aimed to analyze the variables associated with the extracellular matrix in oral pleomorphic adenomas.

Methods: This cross-sectional study comparatively evaluated 21 cases of pleomorphic adenomas and 21 sections of regular oral mucosa from the files of an oral pathology department. The tissue sections were subjected to immunohistochemical study with a monoclonal antibody specific to CD31 protein to assess vascular density and were also stained with Sirius red to evaluate the levels of collagen. The numbers of positively-stained cells were enumerated in specific fields through morphometric study, with subsequent statistical analysis.

Results: Higher numbers of CD31-positive cells were observed in tumor cells than in cells in the regular oral mucosa (P=0.004), which were always located around blood vessels. In tumor lesions, the correlation between the collagen area and vascular density was discrete between these two variables (r=0.046), although the association was not statistically significant.

Conclusions: The results suggested that the increased expression of CD31+ in cells associated with capillaries may be related to tumor neoangiogenesis. Furthermore, an increase in the concentration of collagen fibers proportional to the number of blood vessels in the neoplastic sections suggested the active role of these lesions in the remodeling process.