Expression of calretinin and cytokeratin 19 in radicular cyst, dentigerous cyst, odontogenickerato cyst, and ameloblastoma

Abstract

Context: Calretinin is a protein associated with cellular differentiation and proliferation and is an inhibitor of apoptosis. Cytokeratin is a protein associated with odontogenic epithelial cell, and ameloblasts being epithelial derivative also express some cytokeratin. This study was done to ascertain if calretinin and cytokeratin could be responsible for the differences between aggressiveness of certain odontogenic cysts and tumors. Aims: To evaluate the expression of calretinin and cytokeratin 19 (CK19) in odontogenic cysts and ameloblastoma. Materials and Methods: Sixty samples of formalin-fixed paraffin embedded tissue specimens [15 radicular cysts, dentigerous, odontogenic keratocysts (OKCs), and ameloblastoma] were evaluated for the expression of CK19 and calretinin using immunohistochemistry. Statistical Analysis: Data entry and statistical analysis using Statistical Package for the Social Sciences (SPSS) TM software (version 10.05) were done. Chi-square test was done to compare tissue localization of stain, nature of stain, intensity of stain, and the percentage of cells stained among the study groups. P value less than 0.05 was considered to be statistically significant. Results: Calretinin showed positive expression in all cases of ameloblastoma. Among the samples of OKC, 13% of the cases showed positivity. All the cases of radicular and dentigerous cysts were completely negative for calretinin. CK19 was negative in all cases of radicular cyst and OKC, whereas among the dentigerous cyst two cases showed mild expression and one case showed moderate staining intensity for CK19. Only one case of ameloblastoma showed moderate staining for CK19. Conclusion: The results of this study showed that calretinin can be an immunohistochemical marker for neoplastic ameloblastic epithelium and the difference of expression among the lesions is probably due to their diverse histopathological characteristics and their developmental origin. CK19 a marker of simple epithelia and its absence could probably be due to absence of CK19 epitope, superimposition of other cytokeratins, or masking of the epitopes.