Correlation between numbers of desmosomes and the aggressiveness of transitional cell carcinoma in human urinary bladder

Quantitative electron microscopy has been used to examine the correlation between numbers of desmosomes and the histopathological grade and stage of papillary transitional cell carcinomas in human urinary bladder. Numbers of desmosomes (desmosomal density) per 100 micrometers of cell perimeter were quantitated in 6 examples of normal epithelium, 11 noninvasive papillary transitional cell carcinomas, 8 invasive transitional cell carcinomas arising from papillary lesions, 3 invasive transitional cell carcinomas which had prominent foci of glandular and squamous differentiation, and 1 squamous cell carcinoma. Desmosomal densities were increased in noninvasive transitional cell carcinomas, as compared with normal epithelium, but decreased in invasive transitional cell carcinomas. However, in areas of glandular or squamous differentiation in invasive tumors, desmosomal densities were increased, possibly reflecting the changes in cell phenotype. The decrease in numbers of desmosomes in invasive transitional cell carcinomas may contribute to reductions in cell adhesiveness.