Ultrastructural Resemblance of Basal Cell Epithelioma to Primary Epithelial Germ

The study compared six examples of basal cell epithelioma to fetal and adult skin using five parameters: large aggregates of melanosomes, paucity of half-desmosomes, increased microfilaments, clustered membrane-limited granules, and desmosome-like structures in stromal fibroblasts. These indicators were present in both basal cell epithelioma and fetal hair follicles but absent in fetal and adult epidermis, suggesting that basal cell epithelioma resembled fetal primary epithelial germ. Additionally, stromal fibroblasts in basal cell epithelioma were observed to phagocytize collagen fibers, and membrane-limited granules, potentially zymogen granules for collagenases, were found inside and outside tumor cells near digested collagen stroma.