Monoclonal antibodies Ki-67 and MIB1 in the distinction of tuboendometrial metaplasia from endocervical adenocarcinoma and adenocarcinoma in situ in formalin-fixed material.

This study was undertaken to determine whether immunostaining with the monoclonal antibodies Ki-67 and MIB1 is of use in the distinction of tuboendometrial metaplasia from endocervical adenocarcinoma and adenocarcinoma in situ (AIS) on formalin-fixed, paraffin-embedded tissue. Tissue sections from 100 cases (52 normal endocervix, 27 endocervical tuboendometrial metaplasia, eight endocervical AIS, 13 endocervical adenocarcinoma) were stained with Ki-67 and MIB1 after microwave pretreatment in citrate buffer. Ki-67 and MIB1 labelling indices (LIs) were calculated in each case by determining the percentage of positive-staining nuclei. Five hundred nuclei were counted in each case. Significant differences in Ki-67 and MIB1 LIs existed between the adenocarcinoma group and the tuboendometrial metaplasia group and between the AIS group and the tuboendometrial metaplasia group. No significant differences existed between the adenocarcinoma and AIS groups. Over all groups, the Ki-67 LI was consistently lower than the MIB1 LI. The results indicate that immunohistochemical staining with Ki-67 and MIB1 may be of use in the often difficult histological distinction of tuboendometrial metaplasia from malignant endocervical glandular lesions.