Benign and malignant serous and endometrioid epithelium in the omentum.

OBJECTIVES

Benign and malignant serous and endometrioid epithelial proliferations are found in the omentum, where their presence may be interpreted either as metastases from Müllerian tumors elsewhere or as primary peritoneal tumors. The present study was undertaken in an attempt to gather data that might help resolve the issue.

METHODS

The ratios of serous epithelium to endometrioid epithelium in the omentum, in both the benign and malignant states, were determined for cases from January 1985 to July 1997 and January 1991 to December 1997, respectively.

RESULTS

In ovarian carcinoma, the ratio of malignant serous epithelium to endometrioid epithelium involving the omentum is 15:1. This is comparable to the ratio of benign serous epithelium to endometrioid epithelium in the omentum, which is 10:1. The ratio of primary peritoneal serous carcinoma to endometrioid carcinoma is 10.5:1.

CONCLUSION

It seems not reasonable that endometrioid carcinoma of the ovary is 15 times less likely to metastasize to the omentum than its serous counterpart. The ratio, however, is not unreasonable if endometrioid and serous carcinomas arise from preexisting endometrioid or serous epithelium. We conclude that serous and endometrioid carcinomas may arise primarily in the omentum and, in at least some cases, may derive from their benign counterparts.