Ultrastructural comparison of the interface between epithelium and stroma in basal cell carcinoma and control human skin.

Comparative ultrastructural studies of basal cell carcinomas, seborrheic keratoses, actinic keratoses, and control nontumor skin from human patients demonstrate structural differences between invasive and noninvasive tumor cells. Compared to the other specimen groups, biopsies of basal cell carcinomas reveal a decrease in hemidesmosomes and an increase in actin-like microfilaments in cells at the margins of the tumors. Benign tumors, i.e., seborrheic keratoses and actinic keratoses, have hemidesmosome areas and microfilament contents resembling control nontumor skin. The most striking hemidesmosome areas and microfilament contents resembling control nontumor skin. The most striking increase in microfilaments is in the most infiltrative "morphea" variants of basal cell carcinoma. These findings, in the context of other published reports, suggest that increased microfilaments are related to enhanced motility of invasive carcinoma cells in vivo and that decreased hemidesmosomes may be related to loss of cell to substratum or "anchorage" dependence of growth in malignant cells.