[Serrated lesions of colon and their malignant potential]

To study the serrated lesions of colon and to compare the malignant potential between traditional serrated adenomas (TSA) and conventional adenomas (CAD).

A total of 5347 cases of colorectal polyps encountered in five regional hospitals during a five-year period were retrospectively reviewed. The serrated lesions were classified on the basis of histologic examination. One hundred and eighty-seven cases of CAD (including 160 cases of tubular adenoma and 27 cases of villous adenoma) and 36 cases of invasive adenocarcinoma were randomly selected as the controls. The degree of dysplasia and expressions of Ki-67, p53 and beta-catenin in TSA and CAD were compared.

Amongst the 5347 colorectal polyps studied, 258 cases (4.8%) of serrated lesions were found, which included 112 cases (43.4%, 112/258) of hyperplastic polyp, 78 cases (30.2%, 78/258) of TSA and 26 cases (10.1%, 26/258) of sessile serrated adenoma. Sixty-two cases of TSA were identified from 3 hospitals, in which moderate dysplasia was found in 13 cases. High-grade intraepithelial neoplasia and ICA were found in 6 cases (9.6%). Compared with the 187 cases of CAD, moderate dysplasia were found in 27 cases and high-grade intraepithelial neoplasia and invasive adenocarcinoma were found in 25 cases (13.3%, χ(2) = 19.373, P = 0.000). There was statistically significant difference between TSA and CAD in the degree of dysphasia. The expression of Ki-67, p53 and beta-catenin in TSA and CAD showed no significant difference (P > 0.05).

The incidence of serrated lesions is lower in northern Chinese population than that in Caucasians. TSA has obvious malignant potential; but the rate associated with high-grade intraepithelial neoplasia and invasive adenocarcinoma is lower than that in CAD.