Comparison of cathepsin-D expression in unicystic ameloblastoma, odontogenic keratocyst and orthokeratinized odontogenic cyst using an immunohistochemical method

Cathepsin-D is a well-known protease that promotes invasion in tumoral lesions. Considering the cystic neoplasm nature of odontogenic keratocyst (OKC), the aim of this study was to compare the expression of cathepsin-D in this lesion with the unicystic ameloblastoma (UA) and orthokeratinized odontogenic cyst (OOC) for better understanding of its behavior.

In this descriptive-analytical study, we used paraffin blocks available in the archives of oral and maxillofacial pathology department of dental school (8 unicystic ameloblastoma (UA), 8 odontogenic keratocyst (OKC) and 8 orthokeratinized odontogenic cysts (OOC)) which they were stained immunohistochemically with cathepsin-D. Then, the samples were observed simultaneously by two oral pathologists for detection the intensity and pattern of epithelial and stromal cells staining. Data were analyzed by SPSS20 and Kruskal-Wallis, Mann-Whitney and Chi-square test (P<0.05).

The staining intensity of the epithelial cells of UA group was significantly more than OOC and OKC (P=0.02). The staining intensity of the stromal cells of UA was more than the other two groups, although this difference was not statistically significant (P=0.32). The pattern of cell staining in epithelium and stroma did not show any significant difference between the three groups in this study (P=0.15, 0.22).

The results of this study regarding the intensity expression of cathepsin-D in these three odontogenic lesions could be considered as a probable evidence for the new odontogenic lesions classification (WHO2017) in terms of reintroducing OKC as an odontogenic cyst. If this idea is rejected, it seems that cathepsin-D expression is not associated with the invasive behavior of this cyst, and further investigation of other markers in the epithelium and stroma simultaneously is suggested for a better understanding of its biological nature.