MSN-1 antibody in the evaluation of female genital tract adenocarcinomas

The reactivity of a new monoclonal antibody (MAb), MSN-1, raised against a human endometrial cancer cell line (SNG-II), was studied in a variety of endometrial, endocervical, and ovarian carcinomas as well as normal cycling endometrium. Moderate to strong reactivity (2-3+) was seen in six of nine normal secretory endometria (67%), one of 10 normal proliferative endometria (10%), 18 of 18 endometrial adenocarcinomas (100%), 10 of 11 endometrioid ovarian adenocarcinomas (91%), seven of nine clear cell ovarian adenocarcinomas (78%), one of 12 endometrial hyperplasias without atypia (9%), two of four endometrial hyperplasias with atypia (50%), zero of five endometrial serous adenocarcinomas, two of 17 serous ovarian adenocarcinomas (12%), zero of 10 intestinal-type mucinous ovarian adenocarcinomas, and zero of nine metastatic adenocarcinomas in ovary. Endocervical adenocarcinomas showed moderate to strong staining in 75% (six of eight). It is concluded that MSN-1 can be used to confirm endometrioid/clear cell differentiation in ovarian and endometrial tumors, cannot be used to discriminate endocervical from endometrial differentiation, cannot be used to discriminate atypical hyperplasia from carcinoma, and may be useful to distinguish between atypical (premalignant) endometrial hyperplasias and those without atypia.