Aberrant Crypt Foci in the Background Mucosa of Colorectal Adenocarcinoma

This study was performed in order to determine the histologic features, incidence & frequency of the Aberrant Crypt Foci (ACFs) including mucosal abnormalities arising in the sporadic colonic cancer.

We investigated the proximal and distal colonic mucosa surrounding the tumor in 22 cases (right colon 7 cases and left colon 15 cases) of resected colonic adenocarcinoma specimen. The methylene blue- stained colonic mucosa was examined in en face preparations and rolled totally. The rolled colonic mucosa was embedded in paraffin and examined by using 4micrometer thick serial sections.

We found one hundred twenty two ACFs. The 97 foci (78.7%) were simple hypertrophic foci (SH), composed of more elongated and larger crypts than normal with apical branching associated with goblet cell hyperplasia. The 17 foci (13.9%) were hyperplastic foci (HP) resembling hyperplastic polyp, and 7 (5.7%) were adeno matous foci (AD) while 2 (1.6%) were adenomatous foci with dysplasia (Dys). The mean number of ACFs/cm of the examined mucosa were 0.18+/-0.21 and were higher in the left colon than in the right colon (0.22+/-0.24 vs. 0.10+/-0.10). Immunohistochemical stains for p53 and Ki-67 in these foci revealed strong and upper cryptal staining patterns in AD and Dys of ACFs, like that of neoplasia or preneoplastic condition. However, the staining intensities in SH and HP of ACFs were equal to or lower than that of normal crypts.

These results suggest that grossly defined ACFs include reactive process and the majority of ACFs are induced by simple reactive alteration without preneoplastic potential; and two types of ACFs (AD and Dys) are more likely to be direct precursors of colon tumors than SH or HP.