Reproducibility of histological diagnoses and diagnostic accuracy of non palpable breast lesions.

Twelve pathologists independently examined and classified a set of 25 cases of non palpable breast lesions selected from the archival files of the Pathology Department in Florence. A final consensus diagnosis was reached for all cases at a slide seminar. Individual diagnoses were first combined in 3 broad categories (benign lesion, in situ and invasive carcinoma), then compared to each other and then to the "consensus". Results show that among these 12 pathologists there was complete agreement in 14 cases. Discrepancies for the other 11 cases varied in the number of pathologists and diagnostic categories involved. Overall agreement was excellent (median kappa 0.86) but cases of potentially harmful errors were evident. The authors discuss these findings in the frame of a breast cancer screening program planning.