The role of differentiated dysplasia in the prediction of malignant transformation of oral leukoplakia

ObjectiveOral leukoplakia is the most common oral potentially malignant disorder. Malignant transformation of oral leukoplakia occurs at an annual rate of 1%–7%. WHO‐defined classic epithelial dysplasia is an important predictor of malignant transformation of oral leukoplakia, but we have previously shown in a proof of concept study that prediction improves by incorporation of an architectural pattern of dysplasia, also coined as differentiated dysplasia. We aimed to analyze this finding in a larger cohort of patients.MethodFor this retrospective study 176 oral leukoplakia patients were included. Biopsies for all patients were assessed for the presence of dysplasia and analyzed for cytokeratin 13 and 17 expression. Moreover, the inter‐observer agreement for the diagnosis of differentiated dysplasia was determined.ResultsIn total, 33 of 176 patients developed oral squamous cell carcinoma during follow‐up. Presence of classic epithelial dysplasia increased cancer risk two‐fold (HR = 2.18, p = 0.026). Lesions without classic epithelial dysplasia could be further risk‐stratified by the presence of differentiated dysplasia (HR = 7.36, p