Metastatic Ovarian Carcinoma of Large Intestinal Origin Simulating Primary Ovarian Carcinoma: A Clinicopathologic Study of 25 Cases

The distinction of metastatic ovarian carcinoma from a primary malignant ovarian neoplasm is crucial to its subsequent management. The most common metastatic carcinoma that mimics primary ovarian carcinoma is that of large bowel origin. The clinical and pathologic features of 25 cases of intestinal adenocarcinoma metastatic to the ovaries were analyzed. The patients ranged in age from 47 to 80 years (average age, 60 years). Most patients had abdominal pain and a pelvic mass. In 56%, the ovarian tumors and the large bowel carcinomas were discovered synchronously; 44% were metachronous. Seventy-five percent of the tumors were unilateral. Gross examination revealed that all the ovarian tumors were solid and cystic with smooth outer surfaces. Most of the tumors showed hemorrhage and necrosis. Histologic examination showed that 13 cases had a predominantly endometrioid-like pattern, four cases were predominantly mucinous, and the rest demonstrated a mixed pattern. The presence of a garland pattern with cribriform areas and "dirty" necrosis were the most distinctive features that were helpful in correctly differentiating these tumors from primary endometrioid ovarian carcinoma, with which they are often confused. Immunohistochemical stains for carcinoembryonic antigen showed strong intracytoplasmic positive staining in all the cases of intestinal adenocarcinoma metastatic to the ovaries, in contrast to primary ovarian endometrioid carcinoma, which stain negatively for carcinoembryonic antigen or show only intraluminal or apical positivity. As expected, intestinal adenocarcinoma metastatic to the ovaries had a very poor prognosis. Seventy percent of the patients died within a period of 1 to 19 months (average, 8.2 months). Its distinction from primary ovarian carcinoma is crucial because the management and prognosis of metastatic ovarian carcinoma of large intestine origin is different.