ABSTRACT
The epithelial neoplasms have been divided into two categories: the benign polyps and the malignant carcinomas. By far almost all the cancers of the large intestine are of epithelial origin, sarcomas being extremely rare. The epithelial polyps are protuberant outgrowths arising from the mucosa and compromise the luminal space to a variable degree. Hyperplastic polyps are the most common of polypoid outgrowths from the large intestinal epithelium and generally these have been considered to be nonneoplastic. Juvenile polyps are characterized by abundant fibrovascular connective tissue stroma and large distended crypts, and the name “retention polyp” has also been given to these polyps for that reason. Two morphological types of large intestinal carcinomas have been recognized: the fungating exophytic type and the flat infiltrative “napkin-ring” type. The least common type of carcinoma either in humans or in experimental animals is the squamous cell carcinoma.
