Immunohistochemical Study of Differential Expressions of CAR, E-Cadherin, CK-13, -17, p53 and Ki-67 in Oral Lichen Planus, Lichenoid Lesion and Lichenoid Epithelial Dysplasia

Clinically suspected oral lichen planus (OLP) includes histopathologically proven OLP, oral lichenoid lesion (OLL) or lichenoid stomatitis, and oral lichenoid dysplasia (OLD). Malignant transforming potential of OLD is a diagnostic issue. This study aimed to exclude OLD from OLP and OLL and examine the role of OLD in malignant transformation. Immunostaining for CK13, CK17, p53, Ki-67, Coxsackie‒adenovirus receptor (CAR) and E-Cadherin was conducted in 200 cases. CK13-positive rate was lower in OLD (33.3%) than in OLP and OLL. CK17-positive rate was slightly lower in OLP (89.2%) compared to OLL and OLD. Ki-67positive rate from basal to spinous layer was higher in OLD (30.6%) than in OLP and OLL, and p53 showed similar trend (OLD: 19.4%). Rate of attenuated CAR staining intensity from basal layer to lower one-third of spinous layer was higher in OLD (77.8%) compared to OLP and OLL, similar to rate of attenuated E-Cadherin staining (OLD: 45.8%). In conclusion, a diagnosis of OLP or OLL is indicated when the lesion is CK13 positive and CK17 positive, with no attenuation of staining intensity for CAR and E-Cadherin from the basal layer to the lower onethird of the spinous layer. On the other hand, a diagnosis of OLD is indicated when the lesion is CK13 negative and CK 17 positive, with attenuation of staining intensity for CAR and E-Cadherin from the basal layer to the lower one-third of the spinous layer. In OLD, attenuated CAR expression may participate in malignant transformation by weakening cell junction in the epithelium and inducing epithelial mesenchymal transition.