[Dark epithelial cells in oral premalignant lesions]

Dark basal epithelial cells (D cells) are characterized by a strong affinity for basic dyes and by the high electron density of the cytoplasm and nucleus. These cells have been considered to be putative dedifferentiated precursors of a neoplastic keratinocyte. They are significantly increased in preneoplastic lesions of the human airway and rat trachea induced with chemical carcinogens and/or tumor promoters. Twenty-four cases of oral premalignant lesions were classified as slight, moderate and severe dysplasia, and carcinoma in situ according to the histologic criteria proposed by MacDonald, katz and Pindborg. The percentage of appearance in D-cells of the dysplastic basal layer was calculated and shown as follows: in slight dysplasia 10.6 +/- 0.6%, in moderate dysplasia 22.9 +/- 0.8%, in severe dysplasia 23.9 +/- 0.4%, and in carcinoma in situ 31.4 +/- 0.9%. This result revealed that the increase in the number of D-cells in the basal epithelial layer was in proportion to the severity of the epithelial dysplasia. Thus, the D-cells probably can be used as an indicator in premalignant lesions of the oral cavity.