Immunohistochemical expression of keratins 8 and 19 in odontogenic cysts and tumors

Objective: Cytokeratins (CKs) are integral components in the formation of enamel, dentin and/or cemental matrix and their subsequent mineralization. K8 and K19 are known to be chemically homologous during the formation of tooth structures. This feature is rather unique and is expressed across the milieu of odontogenic tissues in the physiological and pathological states. The present study was designed to evaluate the expressions of K8 and K19 in odontogenic lesions immunohistochemically and to test the hypothesis that they can be used to identify the odontogenic epithelium. Study Design: K8 and K19 were assessed in 60 cases of odontogenic lesions retrieved from the archival files, which included ameloblastoma (18), ameloblastic carcinoma (2), adenomatoid odontogenic tumor (AOT) (9), squamous odontogenic tumor (SOT) (1), odontogenic keratocyst (OKC) (10), dentigerous cyst (10), and radicular cyst (10), including two cases of normal gingiva and follicular tissue. Results: K8 was expressed in 53/60 (88.3%) and K19 in 56/60 (93.3%) odontogenic lesions. The labeling for K19 was found to be more intense compared to that for K8. Further, K8 and K19 were found to be positive in all the gingival and follicular tissues. Conclusions: Positive expressions of K8 and K19 in all the odontogenic lesions studied suggest that these can be used as definitive markers for identifying the odontogenic epithelium. However, the intense and consistent expression of K19 suggests that this CK is extremely sensitive in identifying the odontogenic epithelium.