The accuracy of a frozen section diagnosis of borderline ovarian malignancy.

While the accuracy of frozen section in the diagnosis of invasive ovarian neoplasms has been previously addressed, the frozen section diagnosis of borderline ovarian tumors has been less well characterized. The distinction between benign and borderline lesions is critical to the proper operative management of these patients. The records of 48 patients that had a frozen section diagnosis of borderline ovarian malignancy during surgical exploration between 1986 and 1993 were reviewed. Thirty-one patients were Stage I, 2 patients were Stage II, 10 patients were Stage III, and 5 patients were unstaged. Clarifying phrases were used frequently in the frozen section report, and these terms were categorized as "rule out" borderline tumor, borderline tumor, and "at least" borderline tumor. Of 33 cases with a frozen section report of borderline or at least borderline malignancy, no case were subsequently found to be benign. Errors in the intraoperative management could have occurred in 3 of 48 cases (6.25%), when benign neoplasms were thought to be of borderline malignancy on frozen section. However, in each of these cases, the clarifying term rule out was used, indicating the equivocal nature of the frozen section findings. Thirteen of the 48 patients (27.1%) were found to have a focus of invasive cancer within a borderline tumor on final pathologic review; the primary tumors in these 13 cases ranged in maximal diameter from 5 to 26 cm and were of varying histologic types. The level of experience of the pathologist responsible for the frozen section did not influence the accuracy of frozen section determination noted in this study. A frozen section evaluation identifying a borderline ovarian malignancy is accurate in excluding the presence of benign pathology. It is crucial to understand the meaning of specific clarifying terms used in frozen section diagnoses.