Ultrastructural analysis of the adjacent epithelium of oral squamous cell carcinoma.

Fifteen biopsies of the immediate adjacent epithelium of oral squamous cell carcinoma were examined under light and electron microscopy. Light microscopic examination of one micron thick sections revealed that the majority of lesions (67%) had hyperplastic or mildly dysplastic epithelium while the remaining (33%) had moderate to severe dysplasia. Ultrastructural observations showed that all these lesions had subcellular alterations similar to those seen in frank malignant oral tissue, particularly in the lower half of the epithelium. Important ultrastructural changes observed included bizarre nuclei of basal and lower spinal cells, enlarged and multiple nucleoli, presence of interchromatin and perichromatin granules, loss of desmosomes and marked spongiosis as well as disturbed cellular maturation sequences in the keratinocytes evidenced by abnormal and irregular distribution of maturation markers such as keratohyalin granules and tonofilaments. The present study thus shows the value of electron microscopy in the detection of malignant changes in the adjacent epithelium of oral squamous cell carcinoma.