Histopathological Criteria for Discriminating Adenoma from Carcinoma in the Colorectal Mucosa

Concerning histogenesis of the colorectal carcinoma, it has been generally accepted that the great majority of colorectal adenocarcinomas arises from pre-existing adenoma. However, many contradictions rise into the clinico-pathological relationship between adenomas and carcinomas from the view-point of the histogenesis. Namely, histological criteria for discriminating adenoma from carcinoma is clearly false, because the. criteria is the premise for deducing the histogenesis. On the other hand, the great majority of human malignant tumors develop de novo from each organ and tissue, independently of benign tumors. If we accept the above-mentionedd histogenesis of the colorectal cancer, the large intestine become only one exceptional organ in the human body as to cancer-development, and the theoretical order on human cancer-development is, lost. The nature likes the theoretical order. To answer the natural request, the histological criteria for diagnosing carcinoma should be changed so that a histogenesis "the majority of the colorectal carcinomas arises immediately form the mucosa" may be deduced by premising them, because the clinico-pathological relationship between adenomas and carcinomas of the colorectum, the histogenesis and the histological criteria for diagnosing carcinoma form a logical structure, not independently of each other. Discriminant functions with two variables for differentiating carcinomas from adenomas and doing adenomas from hyperplasia with slight atypia have been objectively derived by image processing. One of the variable is nucleo-cytopmasm ratio in several tubuli, and another is tubular density in a unit area. The histogenesis. of the colorectal carcinomas that major part (70-80%) of the colorectal carcinomas arises immediately from the mucosa, and the remnant (20-30%) dose from adenomas is deduced by using the discriminant functions. According to the functions, cribriform and villous figures are very important to diagnose histologically carcinoma.