Clinico-pathological Evaluation of Oral Leukoplakia with Epithelial Dysplasia

Epithelial dysplasia was examined clinico-pthologically in 199 patients (251 lesions) with oral leukoplakia according to WHO criteria (1978). Of all the lesions, 186 (74.1%) were found to have epithelial dysplasia. The average dysplasia score was 3.3±2.0 points. There was no correlation between the clinical site of lesions and the occurrence of epithelial dysplasia. However, the occurrence of epithelial dysplasia was associated with the clinical appearance of lesions; i. e. erosive-type lesions or verrucous-type lesions. Malignant transformation occurred in 6 patients (3.0%) with oral leukoplakia. In the 12 items of the WHO criteria for epithelial dysplasia, items 1, 3, 4, 6, and 8 were frequently seen, in that order, before malignant transformation. This study suggests that patients with erosive-type lesions or verrucous-type lesions with severe epithelial dysplasia are associated with a greater risk of malignant transformation.