MALIGNANCY POTENTIAL OF COLORECTAL POLYPS - HISTOMORPHOMETRIC, HISTOCHEMICAL AND IMMUNOHISTOCHEMICAL INVESTIGATIONS ON THE DYSPLASIA-CARCINOMA-SEQUENCE
B. Dippe et al., MALIGNANCY POTENTIAL OF COLORECTAL POLYPS - HISTOMORPHOMETRIC, HISTOCHEMICAL AND IMMUNOHISTOCHEMICAL INVESTIGATIONS ON THE DYSPLASIA-CARCINOMA-SEQUENCE, Zentralblatt fur Chirurgie, 120(7), 1995, pp. 556-563
Colorectal polyps are usually diagnosed endoscopically and are simulta
neously removed. Since adenomatous polyps tend to become malignant, th
ese deserve special attention. In order to prevent carcinomas arising
from pre existing adenomas, a precise analysis of the lesions in the m
ucous membrane of the polyps with regard to their malignancy potential
is very important. Morphometric methods and determination of prolifer
ation kinetics enable the dignity of a neoplasia to be assessed. Spora
dic colorectal polyps were examined to what extent the morphometric an
alysis of nuclear area, the silver staining of nucleolar organizer reg
ions (AgNORs) and the immunhistochemical staining of the Ki67 antigen
permit further differentiation of the growth pattern of the tumor. Tis
sue from 50 hyperplastic polyps, 50 tubular and 50 tubulovillous adeno
mas was endoscopically removed and investigated, whereas pure villous
adenomas were not examined due to their relative infrequency. These ti
ssues were compared with biopsies of normal colonic mucosa and also wi
th invasive adenocarcinomas. The Ki67 score shows that the proliferati
ve activity is not significantly different between normal colonic muco
sa and hyperplastic polyps, however there is a noticable difference be
tween the proliferation of the former types and colorectal neoplasias.
The staining of the NORs does not reveal differences between the vari
ous grades of dysplasia in tile adenomas, and therefore proves to be i
nadequate for differentiation, whereas morphometric and immunhistochem
ical measurements reveal appreciable selectivity, No correlation is ob
served between the parameters from the morphometric, histochemical and
immunhistochemical analysis, Using the methods mentioned above the dy
splasia-carcinoma-sequence can be clearly differentiated, however the
validity of the different measurements is very variable. The histomorp
hometric analysis of the nuclear area, and particulary the staining of
the Ki67 antigen seem to present suitable criteria for the differenti
ation of harmless and potentially serious lesions of the colorectum.