Factors involved in skin carcinogenesis.

A personal account of skin carcinogenesis is given based on forty years of investigation of normal and pathologic anatomy of the human skin. Symbiosis of acral portions of adnexa and of melanocytes with epidermal keratinocytes is stressed, and perversion of symbiosis to parasitism in tumor formation is discussed. The role of the basement membrane as a combined effort of, and filter between, ectoderm and mesoderm is stressed, and the nature of basal cell epithelioma as the least differentiated member of the tribe of fibroepithelial adnexal tumors is outlined. Experimental data supporting the promoting role of specific mesodermal stroma in basalioma formation and maintenance are presented.