Intestinal type and endocervical-like ovarian mucinous neoplasms are immunophenotypically distinct entities.

Ovarian mucinous neoplasm (OMN) is traditionally classified as either intestinal type or endocervical-like subtypes. The 2 subtypes represent different clinicopathologic characteristics. The immunophenotype of the 2 subtypes has not been adequately investigated. In this study, we investigated 14 intestinal type OMNs (borderline and adenocarcinoma) and 12 endocervical-like OMNs (borderline and adenocarcinoma) for their expression of PDX-1, CDX-2, CA-125, CK7, CK20, WT-1, D2-40, and TTF-1. We also included 15 colorectal adenocarcinomas metastatic in the ovary, as they may occasionally mimic OMN. The intestinal type OMNs were positive for PDX-1 (100%), CK7 (100%), CK20 (100%), CDX-2 (29%), whereas were negative for CA-125. The endocervical-like OMNs were positive for CA-125 (100%) and CK7 (100%), whereas were negative for CK20, PDX-1, and CDX-2. Metastatic colorectal adenocarcinomas were positive for CK20 (100%), CDX-2 (100%), and PDX-1 (33%), whereas were negative for CA-125 and CK7. All of the intestinal type and endocervical-like OMNs as well as metastatic colorectal adenocarcinomas were negative for WT-1, D2-40, and TTF-1. Our results demonstrated that the intestinal type and endocervical-like OMNs are immunophenotypically distinct entities. The 2 subtypes can be separated from metastatic colorectal adenocarcinoma by the different immunohistochemical profile of PDX-1, CA-125, CK7, CK20, and CDX-2. In the work-up of mucinous adenocarcinoma in the ovary or abdominal cavity, caution should be exercised in interpreting the possible primary site on the basis of the immunohistochemical profiles.