Ultrastructural Resemblance of Basal Cell Epithelioma to Primary Epithelial Germ

The study compared six cases of basal cell epithelioma to fetal and adult skin using five parameters, finding that basal cell epithelioma resembled fetal hair follicles but not fetal or adult epidermis. This resemblance was due to features such as large melanosome aggregates, few half-desmosomes, increased peripheral microfilaments, clustered granules, and desmosome-like structures in stromal fibroblasts. Additionally, stromal fibroblasts in basal cell epithelioma were observed to phagocytize collagen fibers, with membrane-limited granules potentially acting as zymogen granules for collagenases, indicating collagenolytic activity.