[181] Comparison of Immunohistochemical Stains for Myoepithelial Cells Versus Collagen Type IV in Invasive Ductal Carcinomas and Ductal Carcinoma In Situ of the Breast

Jonathan M Kitayama, Robert B West, Kristin C Jensen. Stanford University Medical Center, Stanford, CA; Veterans Affairs Palo Alto Healthcare System, Palo Alto, CA

Background: The differentiation between invasive ductal carcinoma and ductal carcinoma in situ is defined by the absence of myoepithelial cells and disruption of the basement membrane. There are a number of stains that can be used to evaluate for the presence of myoepithelial cells. Few comparative studies of the most commonly used antibodies with significant numbers of cases of ductal carcinoma in situ with (DCIS/IDC) and without (DCIS) invasive ductal carcinoma (IDC) have been performed. We investigated the sensitivity and specificity of five antibodies by staining 319 cases of normal breast, DCIS, IDC and DCIS/IDC on a tissue microarray.
Design: A tissue microarray comprised of normal breast, DCIS, DCIS/IDC and IDC was constructed from cases obtained for the surgical pathology files. Immunohistochemistry was performed using p75 (Santa Cruz Biotech), p63 (Cell Marque), calponin (Dako Cytomation), and smooth muscle myosin heavy chain (SMMS) (Dako Cytomation) and collagen Type IV (Dako Cytomation).
Results: As a whole, all the myoepithelial cell markers had a similar rate of detection for myoepithelial cells in normal breast, DCIS, and combined DCIS/IDC. These rates ranged from 66-85% for DCIS, 53-78% for DCIS/IDC, and 51-67% of normal breast. With invasive carcinoma, there was a wide range of staining ranging from 14% to 100%.

Myoepithelial and Collagen Type IV Positive Cases
p631/7 (14%)96/137 (70%)78/126 (62%)25/49 (51%)
SMMS2/7 (29%)90/137 (66%)67/126 (53%)32/49 (65%)
Calponin4/7 (57%)106/137 (77%)99/126 (79%)33/49 (67%)
p751/7 (14%)116/137 (85%)92/126 (73%)33/49 (67%)
Collagen Type IV7/7 (100%)110/137 (80%)98/126 (78%)30/49 (61%)

Conclusions: In our series, the four myoepithelial antibodies had comparable sensitivity in the detection of myoepithelial cells in normal breast tissue, DCIS, and DCIS/IDC. Those stains with higher sensitivity such as calponin and collagen type IV had lower specificity in comparison to p63. Stains such as calponin and SMMS are easy to visualize but are not as specific as p63. Surprisingly, collagen type IV also showed poor specificity as it stained 100% of invasive carcinomas. It is beneficial to use several myoepithelial stains concurrently when evaluating for invasion. Myoepithelial stains appear to be superior to collagen type IV in our experience.
Category: Breast

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 20, Wednesday Afternoon


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