A Comparative Immunohistochemical Expression of TRAP in Odontogenic Cysts.

Introduction: Tartrate-resistant acid phosphatase (TRAP) is an acid phosphatase metalloprotein enzyme expressed in osteoclasts and is related to bone resorption. The molecular mechanisms involved in the different behavior of odontogenic keratocysts have not yet been fully elucidated. The purpose of this study was to compare TRAP expression in odontogenic keratocysts, radicular cysts, and dentigerous cysts.

Materials and methods: In this cross-sectional study, we selected 60 samples, including 20 cases of each one of the odontogenic keratocysts (OKC), radicular cysts (RC) and dentigerous cysts (DC). The samples were stained with TRAP monoclonal antibodies using immunohistochemistry. The data were analyzed using the Chi-Square and Kruskal-Wallis tests.

Results: In this study, TRAP expression was observed in the lining epithelium of 50% of OKC cases and 5% of RC cases, while it was negative in the lining epithelium of DC. This difference was statistically significant (p<0.001). Moreover, the TRAP staining intensity in the lining epithelium had a significant difference between the groups (P<0.001). TRAP expression in the connective tissue of OKC, RC, and DC was positive in 35%, 30%, and 20% of the cases, respectively. This difference was not statistically significant (P=0.788). Also, staining intensity of TRAP-positive cells in the connective tissue of the lesions was not significant (P=0.634).

Conclusion: In this study, we found a higher expression of TRAP in the lining epithelium of OKC, which may be one of the reasons for the aggressive behavior of OKC compared to other cysts. This finding supports the classification of OKC as an odontogenic tumor.