Comparison of cytokeratin expressions among orthokeratinized odontogenic cysts, epidermoid cysts and odontogenic keratocysts: An immunohistochemical study

BACKGROUND: Orthokeratinized odontogenic cysts are keratinizing jaw cysts and due their association with impacted teeth and keratinaceous content, they resemble odontogenic keratocysts but differ in regards to biological behaviour, being less aggressive. To unravel the nature of OOCs, as they resemble epidermoid cysts histologically and due to their developmental resemblances to OKCs, this study was conducted. AIM AND OBJECTIVE: To compare the cytokeratin expressions of CK 10 and CK 19 among orthokeratinized odontogenic keratocysts, epidermoid cysts and odontogenic keratocysts by immunohistochemical study. MATERIALS AND METHODS: 30 cases of all three cysts were collected, 10 cases in each of these cysts (OOCs, EDCs and OKCs) were incubated with CK 10 and CK 19 markers respectively. IHC staining was performed and assessed all layers of epithelium. All the data were analyzed using SPSS software, P values were obtained by the Chi-square test and Fisher's test. RESULTS: The expression pattern of CK10 showed 100% positive in both OOCs and EDCs with significant difference in OKCs. CK19 expression, between EDCs and OKCs was significant but between OOCs & EDCs and OOCs & OKCs was found to be statistically insignificant. CONCLUSION: CK 10 expressions in both OOCs and EDCs were near identical both in terms of expression and patterns of expression in surface and spinous layers. OOCs may not be distinguished from EDCs both histologically and with CK 10 expression. CK19 expression between OOCs & EDCs and OOCs & OKCs was statistically insignificant. Thus, based upon CK 19 expression, no significant differences were found between OOCs & EDCs and OOCs & OKCs, implying that OOCs resemble both EDCs and OKCs.