Ovarian serous tumors of low malignant potential (serous borderline tumors). The relationship of exophytic surface tumor to peritoneal "implants".

A series of 98 ovarian serous tumors of low malignant potential (LMP) was studied to test the validity of the implantation theory of extraovarian peritoneal spread of tumor by assessing the association between exophytic tumor on the ovarian surface and synchronous peritoneal implants. Patient's ages ranged from 17 to 77 years (mean, 37.8 years). The ovarian tumors were bilateral in 39 cases (40%). Exophytic tumor was present in 47 (48%) cases and involved at least one ovary in 82% of bilateral tumors. Exophytic tumor was found in 29 of 31 patients (94%) with peritoneal implants, but in only 18 of 67 patients (27%) without peritoneal implants. Moreover, 29 of 47 patients (62%) with exophytic tumor had peritoneal implants compared with only 2 of 51 patients (4%) without exophytic tumor. The utility of exophytic tumor as a marker of synchronous peritoneal implants had a diagnostic sensitivity of 94%, a diagnostic specificity of 73%, and an efficiency of 80%. Because of the strongly positive correlation between exophytic tumor and peritoneal implants, the implantation theory remains as a highly likely explanation for extraovarian spread of ovarian serous LMP tumors. The multicentric "field effect" theory, however, cannot be entirely excluded and may be operative in some cases.