Metastatic intestinal carcinomas simulating primary ovarian clear cell carcinoma and secretory endometrioid carcinoma: a clinicopathologic and immunohistochemical study of five cases.

Five cases of ovarian metastases of intestinal adenocarcinomas that suggested the diagnosis of clear cell adenocarcinoma or the secretory variant of endometrioid carcinoma of the ovary are reported. Patient age ranged from 27 to 71 years at the time of diagnosis of the ovarian neoplasms. In four, the ovarian and intestinal tumors were discovered synchronously, and, in the fifth, the ovarian metastasis occurred 1 year after the intestinal primary was diagnosed. The ovarian tumors were unilateral in three patients and bilateral in two. They were up to 18 cm (mean, 12 cm) in maximum dimension and were characterized on microscopic evaluation by glands and cysts lined by cells whose most striking feature was abundant clear cytoplasm. In two cases, striking subnuclear or supranuclear vacuoles were present. An important clue to the diagnosis of metastatic intestinal adenocarcinoma was the presence in all cases of "dirty necrosis." The metastatic nature of the ovarian tumors was supported by the immunohistochemical findings. All tumors stained were strongly positive for carcinoembryonic antigen and cytokeratin 20 and failed to stain for CA125, whereas staining for HAM56 and cytokeratin 7 was absent or only focally positive in one case each. Three intestinal primary tumors involved the small bowel. Microscopic evaluation of the intestinal tumors in three cases and metastases in a fourth, in which the intestinal primary was not resected, showed the features of the uncommon clear cell variant of intestinal adenocarcinoma; the fifth was predominantly a conventional intestinal adenocarcinoma with only a focal clear cell component. Although intestinal adenocarcinomas metastatic in the ovary typically simulate endometrioid adenocarcinoma of the usual type or mucinous adenocarcinoma, they may mimic either primary clear cell adenocarcinoma or the secretory variant of endometrioid adenocarcinoma, particularly when the primary tumor is, even focally, the clear cell variant of intestinal adenocarcinoma.