Differential expression of MUC2 and MUC5AC mucin genes in primary ovarian and metastatic colonic carcinoma

Colonic adenocarcinoma, the most common tumor metastatic to the ovary, may closely mimic primary ovarian adenocarcinoma, especially that of mucinous o r endometrioid histology. The differential diagnosis is important for thera peutic considerations. Mucin gene expression is relatively organ-specific a nd may therefore have use in distinguishing between colonic carcinomas meta static to the ovary and primary ovarian tumors. In this study, we compared the expression of MUC2 and MUC5AC apomucins in 10 colonic adenocarcinomas m etastatic with the ovary, 10 ovarian endometrioid carcinomas (4 primary, 6 metastatic), and 32 primary mucinous ovarian tumors (12 cystadenomas, 10 bo rderline tumors, and 10 cystadenocarcinomas). Monoclonal antibodies CCP58 a nd 45M1 were used for immunostains of MUC2 and MUC5AC apomucin, respectivel y. All but 1 of the 10 metastatic colon adenocarcinomas expressed MUC2, whe reas none expressed MUC5AC. None of the 10 endometrioid carcinomas expresse d MUC2, and only 2 showed weak immunoreactivity with MUC5AC. All 32 primary mucinous ovarian tumors expressed MUC5AC. The percentages of MUC2-positive immunostaining for cystadenomas, borderline tumors, and cystadenocarcinoma s were 0% (0/12), 50% (5/10), and 70% (7/10) respectively. These studies sh ow that MUC2 and MUC5AC are useful markers in the distinction between colon ic carcinoma metastatic to the ovary and primary ovarian carcinoma HUM PATH OL 31:672-677. Copyright (C) 2000 by W.B. Saunders Company.