Occurrence of epithelial dysplasia in oral leukoplakia. Analysis and follow-up study of 12 cases.

The histologic material of 500 leukoplakia patients was analyzed in order to define the characteristics of epithelial dysplasia and to correlate the findings with the clinical data. Epithelial dysplasia was found in 120 cases (24 per cent) and was graded as mild, moderate, or severe. The occurrence of dysplasia was highest in the group of erosive leukoplakias. The majority of the severe dysplasias were found on the tongue and lips. Follow-up studies on sixty-eight leukoplakia patients with histologic dysplasia revealed carcinoma in nine cases (13.2 per cent) during the mean observation period of 6.3 years. Leukoplakias of the tongue showed the highest incidence of malignant change.