Background: Odontogenic cysts are characterized by their sluggish growth and ability to enlarge, primarily affecting the oral and maxillofacial tissues. Timely diagnosis and treatment are crucial to prevent potentially serious consequences. The present study aimed to evaluate and compare the immunohistochemical expression of cytokeratin 19 in the epithelium of odontogenic keratocyst, dentigerous, and radicular cysts.

Methods: This study analyzed forty-five formalin-fixed, paraffin-embedded tissue blocks containing odontogenic cysts. The sample consisted of fifteen odontogenic keratocysts, fifteen dentigerous cysts, and fifteen radicular cysts. Immunohistochemical analysis was performed to assess the expression of the cytokeratin 19 epithelial marker in these samples. Statistical analyses were conducted using Statistical Package for Social Sciences version 26, employing the Chi-square test for comparative analysis of cytokeratin 19 expression among the odontogenic keratocyst, dentigerous cyst, and radicular cyst.

Results: This study showed that 80% of basal layer tissue samples in the odontogenic keratocyst group had negative cytokeratin 19 biomarker scores. In contrast, 60% of dentigerous cyst tissue blocks and 53.3% of radicular cyst tissue blocks were +1. This difference was statistically significant (P = 0.034). In comparison, between groups, there was no significant difference (P = 0.103) in CK19 expression in the surface and spinous layers.

Conclusion: The level of epithelial differentiation is correlated with cytokeratin 19 expression. The cysts with well-differentiated epithelium (radicular cyst and dentigerous cyst) express cytokeratin 19, whereas those with less well-differentiated epithelium (odontogenic keratocyst) exhibit low positives. Thus, it serves as a diagnostic tool for distinguishing these three lesions.