Pathogenesis of Benign Tumors of Cutaneous Appendages and of Basal Cell Epithelioma

THE PATHOGENESIS of basal cell epithelioma has so far not been satisfactorily determined. In this communication, an attempt is made to show that basal cell epitheliomas are not carcinomas but related to the so-called benign epitheliomas, cutaneous adenomas and nevi organomatosi. Evidence will be presented that the tumors belonging to these four groups are nevoid tumors, or hamartomas, originating, in accordance with the Cohnheim theory, from arrested embryonal cells, in this instance from cells of the primary epithelial germ. Variations in the degree and in the direction of differentiation prior to the onset of neoplasia would explain adequately the wide variety of histologic pictures presented. A classification of the tumors originating from the primary epithelial germ will be presented, following which the various types of tumors included in this classification will be discussed. DEVELOPMENT OF THE EPIDERMIS Since my intention is to show that the tumors which are the subject