Expression of Fibroblast Activation Protein-alpha in Odontogenic Lesions – A Retrospective Immunohistochemical Study

The tumor microenvironment (TME) includes cellular and noncellular components that play important roles in tumor genesis, progression, and therapy response. While much study has been done on the TME in other types of cancer, our understanding of its involvement in odontogenic lesions is still restricted. The study group included total (171) odontogenic lesions, which were further divided into two categories. Odontogenic tumors (80) and (2) odontogenic cysts (91). There were 50 cases in the control group. Lymphoma was chosen as the negative control, whereas colorectal and breast carcinomas were chosen as the positive controls. All groups were immunohistochemically stained with the fibroblast activation protein (FAP)-alpha antibody. The samples from the study groups were compared to clinical parameters and statistically evaluated using the Chi-square and Kendall’s tau tests. Unpaired t-test was used to compare the final immune reactivity score (IRS) with the presence or absence of epithelium, radiographic locularity, and ramus involvement. Cronbach’s alpha was used to calculate inter-rater reliability. The ameloblastoma tumor group and the odontogenic keratocysts in the cyst group showed a high mean IRS. When the final IRS was compared to a few clinical characteristics such as lesion extension and ramus involvement, showed statistical co-relation. With significant connections between the final IRS and a few clinical features, FAP-alpha appears to be a reliable marker for odontogenic lesions. It could be employed as a therapeutic and prognostic marker in future.