Influence of immunohistochemistry on the final diagnosis of breast biopsies

Because of the introduction of mammography screening programmes in Europe, the number of breast biopsies performed is increasing. We investigated the influence of immunohistochemistry (IHC) on the final diagnosis of breast biopsies by comparing the primary diagnoses (based on the results of haematoxylin and eosin staining only) with the final diagnoses (based on the additional information provided by IHC).

We analysed the breast biopsies which were performed at the University of Halle-Wittenberg between 2006 and 2010 and for which the pathologist requested IHC for making the final diagnosis. According to the B-categorization scheme, the primary diagnosis changed in 37 of a total of 429 biopsies (8.6%). In 18 of these biopsies (48.6%) the category changed from B1-B2 to B3-B5 or vice versa, which would imply a different work-up. Only 77% of the primary diagnoses of breast cancer in situ were confirmed.

IHC has a considerable influence on the final diagnosis of breast biopsies in several situations, including those in which the biopsied women are at risk of inadequate therapeutic intervention. The influence is particularly notable among those biopsies for which IHC is performed in order to assess the suspicion of breast cancer in situ.