Carcinoma in Situ Contrasted With Benign Penetrating Epithelium

Before I undertake to point out the importance of bringing into the category of carcinoma certain so-called entities that for the most part have remained outside of this category and to exclude from this category epithelial hyperplasia that is not of carcinomatous nature, I believe it is essential to emphasize established facts. These are that the entity called carcinoma or cancer, regardless of etiology, is a primary disease of epithelial cells, and that all other phases and sequelae, although of great importance, are in reality of secondary nature. Carcinoma in situ is a condition in which malignant epithelial cells and their progeny are found in or near positions occupied by their ancestors before the ancestors underwent malignant transformation. At least they have not migrated beyond the juncture of the epithelium and connective tissue or the so-called basement membrane; such migration would be manifested by the cells entering the connective tissue