Immunohistochemical Evaluation of CK19 Tumor Marker in Inflamed and Non Inflamed Odontogenic Keratocyst Groups

Odontogenic keratocyst (OKC) or keratocystic odontogenic tumor (KCOT) is a developmental odontogenic cyst which requires special attention due to its unique clinical and histopathological features. CK19 is expressed in non-keratinized normal epithelium and its expression increases during inflammation. Recently the use of this tumor marker has been suggested for identification of odontogenic cysts and tumors. Thus the aim of the present study was to evaluate the expression of CK19 in inflammatory and non-inflammatory keratocyst epithelial cells. This retrospective cross-sectional study was performed immunohistochemically on 25 inflamed and non-inflamed OKC paraffin blocks retrieved from the Archives of the Oral Pathology Laboratories of Isfahan Azad University and Isfahan University of Medical Sciences Medical Faculties. After selecting the samples, sections measuring 3‒5 µm in thickness were prepared. The intensity of cytoplasmic stainability was studied immunohistochemically in three different layers of cyst epithelium: basal, suprabasal and superficial under a light microscope at ×10 and ×40. Data were analyzed with Mann-Whitney test using SPSS 20 (α = 0.05). Expression of CK19 was seen in 100% of inflammatory OKCs and 84% of non-inflammatory OKCs. In inflamed OKCs expression of CK19 was seen in all the three layers of epithelium; however, in non-inflamed OKCs expression of CK19 was seen in the middle layer in only one sample (p value < 0.001). According to the results of the present study, CK19 was expressed in both inflammatory and non-inflammatory OKCs; however, the intensity of staining was different between the groups. In contrast to oral mucosal lesions CK19 was expressed in keratinized odontogenic epithelium. In odontogenic keratocyst, expression of CK19 was seen in response to inflammation as seen in oral lesions.