Immunohistochemical evaluation of epidermis overlying basal cell carcinomas

We have examined the character and carcinogenic properties of the normal-appearing epidermis overlying basal cell carcinomas by immunohistochemical methods, employing a series of monoclonal antibodies. The labelling index was significantly increased in the atrophic epidermis overlying basal cell carcinomas (solid type, n=20). compared with the epidermis overlying or adjacent to squamous cell carcinoma (n=20). keratoacanthoma (n= 10). dermatofibroma (n=10), neurofibroma (n= 10). soft fibroma (n=10). pyogenic granuloma (n=10) and cutaneous leiomyoma (n=5). Cells which expressed epidermal growth factor (EGF) receptor were detected in all layers of the epidermis over the basal cell carcinomas, hut not the other tumours. Basement membrane-related antigens, including bullous pemphigoid antigen and GB3 antigen, were decreased in the epidermis. AEl. the monoclonal antibody against basal cell keratin, reacted with the uppermost layers of the normal-appearing epidermis overlying the basal cell carcinomas. ICAM-1 expression was very weak in the overlying epidermis. The dermis subjacent to the proliferating epidermis showed staining for transforming growth factor-α (TGF-α). strong positive PECAM-1 staining of endothelium. and numerous HLA-DR-positive cells. From these results, we suggest that the proliferative activity in the epidermis overlying basal cell carcinomas is not a state induced by the dermal infiltrate, but represents carcinogenic activity of the epidermis.