Dark cells in human oral leukoplakias.

Dark basal keratinocytes, characterized by a strong affinity for basic dyes and by electron density of cytoplasm and nucleus, could be recognized in eleven oral leukoplakias. The percentage of dark cells was higher in the group comprising leukoplakias verrucosa, and erosiva (28% of the basal cells) than in the leukoplakia simplex group (10%). The presence of these cells is a good indicator of the degree of histological dysplasia and correlates well with the preneoplastic potential of these lesions.