Accuracy of frozen section diagnosis: a retrospective analysis of 4785 cases.

During a 1-year period 4785 intraoperative consultations were performed. The pathology reports were retrospectively reviewed to determine the accuracy of frozen section diagnosis in various tissue types. Skin for evaluation of section margins and axillary sentinel lymph nodes for evaluation of metastatic disease were most frequently sent for frozen section diagnosis. The number of discordant cases were 182, 178 were false negative and four were false positive. When frozen section diagnoses were compared with permanent section diagnoses, the overall diagnostic concordance was 95.1%. The number of deferred specimens was 57. The accuracy of frozen section diagnosis varied between tissue types, and axillary sentinel lymph nodes accounted for the greatest number of discordances. In conclusion, the frozen section diagnosis is a reliable method with varying concordance and deferral rates between tissue types. We suggest regular monitoring of the performance in frozen section diagnosis.