[238] Clinical Utility of a p63-CK7/18-CK5/14 Antibody Cocktail in Diagnostic Breast Pathology.

Emily S Reisenbichler, John R Ross, Omar Hameed. University of Alabama at Birmingham

Background: An antibody cocktail directed against p63, cytokeratin (CK)5/14 and CK7/18 (Biocare) is reported to be useful in distinguishing non-invasive from invasive breast lesions as well as for the characterization of intraductal epithelial proliferations. There are, however, limited studies that evaluate its use in clinical practice.
Design: A retrospective review of all breast material at a university medical center was performed to identify cases that were immunostained with the above antibody cocktail. The clinical, radiological and pathological findings were reviewed to determine the indication(s) for immunohistochemistry, quality of staining, and interpretation of findings. Additional p63 immunostaining alone was performed to further determine the utility of the antibody cocktail in the evaluation of invasion.
Results: The antibody cocktail was performed on 2.3% of breast cases over a 6 month period.
There were 44 cases that were immunostained to confirm or exclude invasion. Twenty two (50%) of these had easily-identifiable p63/CK5/14-positive myoepithelial cells, while the remainder lacked any such staining confirming the diagnosis of invasive carcinoma. In 27 cases with available diagnostic material for additional p63 immunostaining, the cocktail better highlighted myoepithelial cells by staining both nuclei and cytoplasm. Easier identification of invasion was also facilitated by the moderate to strong CK7/18 expression seen in invasive foci, especially those composed of single cells.
There were 10 cases that were immunostained to help determine the nature of an intraductal proliferation. The cocktail demonstrated a mosaic staining pattern of both CK7/18 and CK5/14 positive epithelial cells in 3 (30%) cases consistent with usual hyperplasia; homogenous CK7/18 expression in the remaining cases supported the diagnosis of atypical ductal hyperplasia or carcinoma in-situ.
Conclusions: The most frequent use of a p63-CK7/18-CK5/14 antibody cocktail was to evaluate for the presence/absence of invasive carcinoma. While p63 alone is of proven diagnostic utility (as are other myoepithelial markers), the antibody cocktail appears to be more useful because of both better labeling of myoepithelial cells and labeling of invasive tumor cells on the same section. This might be crucial in cases with minute foci of invasion, where the inclusion of a “positive stain” can lend more support to the diagnosis of carcinoma than just relying on the absence of myoepithelial cell staining. The antibody cocktail also aided in the distinction between hyperplastic and atypical/carcinomatous intraductal proliferations.
Category: Breast

Wednesday, March 2, 2011 1:00 PM

Poster Session VI # 23, Wednesday Afternoon


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