Mucinous tumors of the ovary: diagnostic challenges at frozen section and clinical implications.

OBJECTIVE: Frozen section (FS) diagnosis of mucinous tumors of the ovary can be quite difficult due to the size of these tumors, heterogeneity and potential risk of metastasis from gastrointestinal (GI) neoplasms. Given the paucity of data on this subject, our objective was to determine the reliability of FS diagnosis in ovarian mucinous tumors. METHODS: A retrospective review of 73 consecutive ovarian mucinous tumors submitted for frozen section (FS) evaluation between January 2004 and November 2009 was conducted. FS and final pathology results, in addition to patient characteristics, were collected. Univariate analysis was performed evaluating predictors of FS reliability. RESULTS: The average tumor size was 19.7cm (0.8-50cm). The FS and final pathology diagnosis were concordant in 66% (48/73) of the cases. Of the 25 (34%) discordant cases, 8 (11%) were downgraded and 17 cases (23%) were upgraded. Of the 44 tumors interpreted as LMP on FS, 14 (32%) were malignant at final diagnosis (26% ovarian, 7% GI) and 8 (18%) were benign. Of the 23 benign tumors on FS, 13% were upgraded to either LMP or malignant at final diagnosis. Tumors with a malignant diagnosis on FS were 100% concordant with final diagnosis. Univariate analysis did not reveal any correlation with the FS diagnosis and patient age, tumor size or presence of bilateral disease. CONCLUSIONS: Our study showed a 34% rate of discordance between FS and final diagnosis. Given that 5 cases (7%) were of GI origin, intraoperative assessment of the appendix should be performed in all mucinous ovarian tumors.