This study investigated the correlation between clinical and histopathological findings in 171 cases clinically diagnosed as oral leukoplakia. Histopathological examination revealed squamous cell carcinoma in 14 cases, leukoplakia with epithelial dysplasia in 68 cases, and hyperkeratosis without epithelial dysplasia in 89 cases. According to the grade of epithelial dysplasia, the leukoplakias were classified into mild, moderate, severe epithelial dysplasia and carcinoma in situ, which included 49, 14, 3 and 2 cases, respectively. High grades of epithelial dysplasia were mainly observed on the lateral edge of the tongue or the oral floor. There was a close correlation between the clinical appearance of lesions and a high grade of dysplasia; the majority of the cases with high grades of dysplasia or with early invasive carcinoma clinically showed erosive-type lesions.
