Frozen section diagnosis: a quality control study.

In a quality control study we reviewed six hundred and eighty one frozen section specimens sent to our department from 1981 to 1989. Accuracy was 98%. Diagnosis was deferred in 1%. False positive diagnosis for malignancy was made in one (0.15%) case and false negative diagnosis for malignancy in thirteen (2%) cases. Most of the inaccurate diagnoses concerned the female breast and the omentum. Incorrect diagnoses were due to interpretation of the pathologic findings (50%), to microscopic sampling (36%) and to gross sampling (14%). Some of the lesions are difficult to diagnose even in permanent sections. Technical skill and diagnostic expertise are essential for high diagnostic accuracy in the method of frozen section.