Premalignant oral mucosal diseases.

A premalignant phase in the development of oral cancer is predicted by the classic model of experimental epithelial carcinogenesis. Virtually all oral squamous cell carcinomas arise from a premalignant precursor, but it is difficult to specifically define the term premalignant. Oral pathologists use the term epithelial dysplasia to indicate microscopic features in a biopsy specimen that are associated with a risk of malignant change and then assign a grade of severity. There is good correlation between higher grades of dysplasia and increasing risk of cancer but less so with the lower grades. The clinical appearances manifested by oral epithelial dysplasia and early oral cancer include leukoplakia, erythroplakia, and speckled leukoplakia. This paper discusses and illustrates these clinical lesions, their associated risk factors, their relationship to epithelial dysplasia, and the associated risk of evolution into oral cancer.