Utility of Frozen Section in the Evaluation of Borderline Ovarian Tumors: A Single Institution Experience

Background: Borderline ovarian tumors (BOTs) account for a 10-15% subset of all primary ovarian epithelial neoplasms. Preoperative imaging and serologic markers are often inconclusive at distinguishing between benign, pre-malignant, and malignant ovarian tumor. Limitations at time of frozen section (FS) are relatively well known, and misinterpretation may occur potentially leading to over- and under-treatment. We evaluated all cases of BOTs submitted for FS in our institution to determine the accuracy of intraoperative diagnosis when compared with the final pathology, and possibly identify features that may guide surgical staging decision-making. Methods: We identified all intraoperative diagnoses of BOTs from our institution in a 12-year period. Clinical and pathologic data were abstracted. Intraoperative pathology diagnosis was compared to final pathologic diagnosis. Statistical analysis was performed using chi-square and logistic regression. Results: There were 80 cases included for analyses, of which 39 (48.8%) were serous borderline tumor (SBT), 18 (22.5%) mucinous borderline tumors (MBT), 1 (1.2%) endometrioid borderline tumor, and 22 (27.5%) at least borderline tumor (of various histologies). There were 13 cases with a discrepancy between FS and final diagnosis. In patients with a discrepancy where final pathology demonstrated carcinoma, 4/11 (36.3%) were not staged or had incomplete staging. Subsequently, 3/4 (75%) underwent a re-operation for staging purposes. In patients with discrepant pathology, discrepancy was more common 8/37 (21.6%) among non-gynecologic pathologists compared to 5/43 (11.6%) among gynecologic pathologists, but not statistically significant (p=0.23). When “at least borderline” tumor was diagnosed at FS, 10/22 (45%) had invasive malignancies on final pathology compared to diagnosis of BOT “only” on FS; on which 1/58 (1.7%) had invasive carcinoma. The cases with histologic diagnosis of BOT “only” were associated with significantly reduced discrepancy (OR 0.04 [95% CI 0.01-0.18], p< 0.001). Conclusion: In conclusion, use of intraoperative evaluation for ovarian tumors is a useful diagnostic tool but has its limitations. In intraoperative cases where pathologists call “at least borderline”, strong consideration for surgical staging should be contemplated with re-evaluation of preoperative testing. Moreover, when possible, direct communication between surgeon and pathologist at time of FS diagnosis of BOT may be valuable.