Prediction of malignant change in oral precancerous lesions by DNA cytofluorometry

In order to investigate the possibility of predicting malignant transformation of oral precancerous lesions in the initial biopsy specimens, Feulgen‐DNA cytofluorometry was applied to the initial biopsies of 7 cases of leukoplakia and one of lichen planus which later showed malignant transformation, using smears of squamous epithelial cells isolated from thick paraffin sections with non‐specific fluorescence blocking. Analysis of DNA ploidy patterns revealed that “dysplastic changes” of DNA histograms in cases with epithelial dysplasia tended to be expressed by a shift of the modal peak to hyperdiploid values and by an increased number of cells in 2.5 C to 3.5 C and hyper‐4 C, regardless of the prognosis. However, in the cases with subsequent malignant transformation, the DNA histogram was characterized by the appearance of bimodal peaks.