Frozen section diagnosis of breast lesions. Recent experience with 556 consecutive biopsies.

Experiences with frozen sections performed on 556 consecutive breast biopsies were reviewed. There were no false positive reports among the 145 (26%) lesions interpreted as carcinoma. Among 381 (68.6%) biopsies in which no carcinoma was found on frozen section, eight proved to contain carcinoma in other areas. Seven of the false negatives contained noninvasive carcinoma (six--in situ lobular; 1--intraductal). A small infiltrating lesion was found in the eighth case. The diagnosis was deferred to paraffin section in 30 (5.4%) of biopsies. Ten lesions proved to be noninvasive carcinoma and one was an infiltrating lobular carcinoma. Frozen section diagnosis is a highly reliable procedure for the diagnosis of infiltrating breast carcinoma. Noninvasive carcinoma may be overlooked at frozen section because of the limitations of sampling. Consequently, patients should be cautioned to await the paraffin section report if the frozen section does not reveal carcinoma. A frozen section diagnosis of carcinoma does not necessarily commit the surgeon to further surgery at that time and the information obtained from the frozen section may be helpful in beginning to plan further treatment with the patient.