The borderland between benign and malignant surface epithelial ovarian tumors. Current controversy over the nature and nomenclature of "borderline" ovarian tumors.

In the early 1970s, the International Federation of Gynecology and Obstetrics (FIGO) and the World Health Organization (WHO) adopted the terms "borderline malignancy" and "carcinoma of low malignant potential" in their classifications of surface epithelial tumors of the ovary in order to denote a subset of patients with a significantly more favorable prognosis than those with the "usual" surface epithelial carcinomas. Subsequently, a considerable clinicopathologic body of literature has arisen concerning borderline tumors, particularly the serous and mucinous types. Some of them, particularly advanced stage borderline tumors, have been purported to cause significant illness and death. However, some investigators have impugned their malignant nature, especially in Stage I disease, and blame the suggested poor prognosis in advanced cases on a paucity of accurate morbidity and mortality data and ambiguity in current histopathologic terminology; to address the latter, they have proposed to remove any connotation of malignancy by replacing the aforementioned terms with designations such as "atypical proliferating (serous or mucinous) tumor." Another soon-to-be proposed classification will use the terminology "borderline tumors" as a generic group without destructive invasion but with subdivisions into tumors with "epithelial atypia" and those with "intraepithelial carcinoma." The clinical and therapeutic implications of accurate diagnosis of ovarian borderline tumors mandate additional investigation to elucidate their true prognosis; indeed, further dialogue is necessary to arrive at a nosologic system to reflect that biologic behavior. However, until a consensus has been reached, the pathologic diagnosis should reflect, at some point, the currently sanctioned FIGO/WHO classification of surface epithelial ovarian tumors to obviate any misunderstanding that could lead to patient mismanagement.