Diagnostic discrepancies in breast specimens subjected to gross reexamination.

To determine the accuracy of gross examination of breast specimens from a large university pathology service, 1120 breast specimens submitted from 1995 to 1997 that had residual tissue after submission of tissue sections were reexamined for diagnostic discrepancies. A total of 520 mastectomies, 143 wire localization excisions, 156 lumpectomies, and 301 mammoplasties were reexamined. Fifty-three (5%) major and 65 (6%) minor diagnostic discrepancies were detected. Major discrepancies included eight additional positive lymph nodes, 37 missed cancers, four upstagings by size, and four skin invasions. Forty-four of the major discrepancies were in mastectomy specimens. First-year residents accounted for slightly more than one half of all discrepancies. In contrast, review of original slides of 733 breast cancer cases revealed only 11 (1.5%) major discrepancies: three changes of margin status, six missed carcinomas, one positive lymph node, and one upstaging by size. Most discrepancies occurred because a specimen was not thoroughly inspected. The second most common cause was failure to recognize lesions. Our findings suggest that gross dissection performed by first-year residents is more prone to error and that such discrepancies are amenable to instruction and supervision.