[The malignancy potential of colorectal polyps--histomorphometric, histochemical and immunohistochemical study of the dysplasia-carcinoma sequence].

Colorectal polyps are usually diagnosed endoscopically and are simultaneously removed. Since adenomatous polyps tend to become malignant, these deserve special attention. In order to prevent carcinomas arising from pre existing adenomas, a precise analysis of the lesions in the mucous membrane of the polyps with regard to their malignancy potential is very important. Morphometric methods and determination of proliferation kinetics enable the dignity of a neoplasia to be assessed. Sporadic colorectal polyps were examined to what extent the morphometric analysis of nuclear area, the silver staining of nucleolar organizer regions (AgNORs) and the immunohistochemical staining of the Ki67 antigen permit further differentiation of the growth pattern of the tumor. Tissue from 50 hyperplastic polyps, 50 tubular and 50 tubulovillous adenomas was endoscopically removed and investigated, whereas pure villous adenomas were not examined due to their relative infrequency. These tissues were compared with biopsies of normal colonic mucosa and also with invasive adenocarcinomas. The Ki67 score shows that the proliferative activity is not significantly different between normal colonic mucosa and hyperplastic polyps, however there is a noticeable difference between the proliferation of the former types and colorectal neoplasias. The staining of the NORs does not reveal differences between the various grades of dysplasia in the adenomas, and therefore proves to be inadequate for differentiation, whereas morphometric and immunohistochemical measurements reveal appreciable selectivity. No correlation is observed between the parameters from the morphometric, histochemical and immunohistochemical analysis. Using the methods mentioned above the dysplasia-carcinoma-sequence can be clearly differentiated, however the validity of the different measurements is very variable.(ABSTRACT TRUNCATED AT 250 WORDS)