Dysplasia is commonly seen in the speckled and erosive type of leukoplakia.
A comparative study on the ultrastructure of dysplasia with carcinoma would be instructive when erosive type leukoplakia of is differentiated from the carcinoma.
We studied the organelles of cells leukoplakia of simple, verrucous and erosive type and both early and invasive carcinoma in relation to the changes of the basment membrane underlying these lesions.
21 cases of leukoplakia, 14 cases of early and invasive carcinoma and 4 cases of normal mucosa were examined with ligh and electron microscopes (HITACHI H-600). The specimens were carefully selected to investigate the ultrastructure of basal cells and adjacent basement mebrane.
Leukoplakia of erosive type showed a close similarity in the ultrastructure to early and invasive carcinomas in the following points:
1) Increased nuclear to cytoplasmic ratio, indentation of nuclear membrane, enlarged nucleolus and increased chromatin content near the nuclear membrane.
2) Increased size of basal cells at the basement membrane.They have pleomorphic mitochondria with distinct crista and well-developed rough endplastic reticulam and Golgi apparatus.
3) Loosing of the intercellular space due to underdevelopment of cell junctions such as tonofilament, desmosome and hemidesmosorne.
4) Increased cytoplasmic processes with finely villous and branched structures. They penetrate the basement membrane and protrude into the stroma.
5) The varied morphology of the basement membrane including disruption, thickening, disappearance, stratification, branching and doubling.
The ultrastructural study on the basal cells and basement membrane of erosive leukoplakia showed a close similarity to those of early and invasive carcinomas.