There are some fourteen different types of simple tumors. Each is due to the proliferation of one variety of cell. The epithelial tumors form the largest group of the simple tumors and their pathology has already been presented to you. The remaining tumors are often called the connective tissue tumors because many of them are of mesenchymal origin. The broader and better term to designate them when placed in contrast with the epithelial tumors is the non-epithelial tumors. It remains for me to present to you as dermatologists certain points of interest concerning the pathology of this large variety of tumors, some of which you see frequently, others rarely or not at all.
CLASSIFICATION AND TYPE OF CELL
A word first in regard to the classification of tumors. Under every recognized variety of tumor should be grouped both the slowly and the rapidly growing tumors built up by the multiplication
MALLORY FB. PATHOLOGY OF MALIGNANT DISEASES OF NON-EPITHELIAL FORMATION. JAMA. 1910;55(19):1621–1623. doi:10.1001/jama.1910.04330190017005