Classification of colorectal adenomas with quantitative pathology. Evaluation of morphometry, stereology, mitotic counts and syntactic structure analysis.

In search for an objective classification rule for the morphologic changes in colorectal adenomas, the results of nuclear morphometry for assessing geometric characteristics of tumour nuclei, syntactic structure analysis for assessing the arrangement of nuclei in the epithelium, stereological assessment of glandular changes, and area weighted mitotic counts were evaluated in a multivariate analysis. The H&E stained tissue sections of 59 colorectal adenomas were studied, of which 20 showed mild, 20 moderate and 19 severe dysplasia, according to blind duplicate assessments by two pathologists. In a stepwise jackknifed discriminant analysis, the combination of variables was selected that could best discriminate the cases into the previously assessed grade of dysplasia. With the combination of two variables (minimum line length and inner gland surface density), 71% of the cases could be correctly classified according to the previously assessed grade. No cases with mild dysplasia were classified as severe dysplasia and vice versa. However, since the reproduction of subjectively assessed grade was not the ultimate goal, we aimed to discriminate the cases into two groups on the basis of measurements results alone, by means of a cluster analysis. These two groups would merely reflect the cases with major versus minor morphologic changes. The results of the cluster analysis showed that all mild dysplasia cases were allocated into the low grade cluster, and that the moderate dysplasia cases were divided over both the low grade and high grade cluster. Two severe dysplasia cases with borderline morphometric results were allocated into the low grade cluster, and the remaining 16 into the high grade cluster. It is concluded that objective evaluation of dysplasia in colorectal adenomas is possible by a combination of morphometric techniques. The results of the morphometric analyses seem to favor a two-grade classification system rather than a three-grade system.