Tumor of low malignant potential (LMP tumor)

Ten to fifteen percent of epithelial ovarian tumors are considered borderline malignancies. They tend to occur in women in their forties and fifties, younger than those with frankly invasive tumors, and they are not thought to be related to hereditary breast/ovarian cancer syndromes. These tumors are stage I at diagnosis in more than 90% of patients, have infrequent recurrence, and an excellent prognosis. The survival rates for stage I and stage III are close to 100% and 80% to 90%, respectively. The survival is good even in patients who have developed peritoneal spread. Just more than half are serous, with the rest being mucinous and occasional mixed intestinal cell or endometrioid types. The mucinous tumors tend to be unilateral and are most often of the intestinal type, with a minority being of the endocervical type. Serous tumors have a higher incidence of bilaterality.

The typical ultrasound appearance of a borderline ovarian cancer is a complex cystic mass with septations, nodularity/papillations, and irregular walls. Flow is typically identified in the solid areas, although not so much flow nor so many irregular vessels as are usually seen in invasive cancers. This difference is neither sufficient nor reliable enough to differentiate invasive from borderline tumors accurately sonographically.

The sonographic appearance of borderline tumors is often similar to that of invasive cancers. Other diagnostic possibilities include a decidualized endometrioma in a pregnant woman (see Endometriosis) or a cystadenofibroma. Typically the cystadenofibromas and benign cystadenomas have smaller areas of nodularity with little if any blood flow within the nodule or septae.