Evaluation of Mast Cell Density and Expression of Immunohistochemistry Matrix Metalloproteinase-9 Oral Squamous Cell Carcinoma

Squamous cell carcinoma is one of the most common malignancies in the oral cavity. The number and distribution of mast cells affect the pathogenesis of oral squamous cell carcinoma (OSCC). Mast cells can produce enzymes, such as matrix metalloproteinase-9 (MMP-9) that can affect OSCC growth and the aggressive behavior of tumors. This study investigated the mast cell density and immunohistochemical expression of MMP9 in OSCC.

In this descriptive study, 10 paraffin blocks of OSCC were selected from the pathology department archive in the Dentistry College of Jundishapur University of Medical Sciences and Imam Khomeyni Hospital in Ahvaz, Iran. Afterward, 4-µm sections were cut from paraffin blocks and stained using the immunohistochemical method for MMP9 expression and using toluidine blue for mast cell count. The expression of MMP9 in the epithelium and connective tissue was investigated, and the number of mast cells was counted in five high-power fields.

In this study, MMP9 was expressed (over 50%) in eight cases in the epithelium and nine cases in connective tissue. In one case, MMP9 was not expressed in the epithelium. No statistically significant association was observed between immunohistochemical expression of MMP9 in connective tissue and the mean number of mast cells in OSCC connective tissue. One of the specimens was excluded from this study due to the low amount of tumor tissue.

Expression of MMP9 in the connective tissue of all cases may indicate the aggressive behavior of OSCC; however, this expression may not be related to mast cell density or may be suppressed with a high number of mast cells.