Grading schema are based upon the microscopic appearance of a neoplasm with H&E staining. In general, a higher grade means that there is a lesser degree of differentiation and the worse the biologic behavior of a malignant neoplasm will be. A well-differentiated neoplasm is composed of cells that closely resemble the cell of origin, while poorly differentiated neoplasms have cells that are difficult to recognize as to their cell of origin. Grading schema have been devised for many types of neoplasms, mainly carcinomas. Most grading systems have three or four grades (designated with numbers or roman numerals).
In the diagram below utilizing an adenocarcinoma as an example, the principles of grading are illustrated:
|Grading of Malignant Neoplasms|
|I||Well differentiated (高分化)|