[314] Feasibility and Potential Utility of IPX Cocktail Double Stain in Breast Cancer

PA Tsivis, D Coppola, B Babbin, D Tacha, MM Bui. Moffitt Cancer Center, Tampa; Physicians RightPath, Tampa; Biocare, Concord

Background: The usefullness of cocktail antibody (cytokeratin 903, P63 and racemase) with double stain in the diagnosis of prostatic adenocarcinoma inspires the desire to develop a similar antibody cocktail for breast cancer. Although no equivalent known markers differentiating benign versus neoplastic epithelium, lacking of myoepithelial cells is a diagnostic feature of invasive mammary carcinoma. This study evaluated a novel IPX cocktail double stain in the diagnosis of breast cancer.
Design: IPX (Biocare, Concord, CA) composed of primary antibodies cytokeratin 5 (CK5), CK14 and p63 and secondary antibody CK18. Thirteen mastectomy or lumpectomy specimens were retrospectively reviewed to identify invasive or in situ carcinoma, atypical or usual ductal hyperplasia (ADH or UDH), adenosis and normal breast. 4-um sections were obtained from selected formalin fixed and paraffin embedded blocks to stain with IPX cocktail following the manufactures recommendation. Appropriate negative and positive controls, and p63 stain were performed in parallel.
Results: Nineteen tissue sections selected consisting invasive ductal carcinoma (12), invasive lobular carcinoma (1), ductal carcinoma in situ (12), ADH (1), UDH (2), adenosis (2) and normal breast (19). CK18 stained the cytoplasm of the epithelium uniformly red without discrimination of benign versus malignant component. It was useful in identifying small foci of epithelial cells or cells arranged in single file, especially when there was prominent lymphocytic infiltration or desmoplastic background masking the foci of interest. The myoepithelial markers stained the nuclei (P63) and cytoplasm/membrane (CK5 and CK14) brown contrasting nicely against the red epithelial component. It better highlighted the myoepithelial cells than p63 stain alone. The invasive carcinoma completely lacks the brown stain; in situ tumor stained at the peripheral/basal layer. Basal and intraparenchymal stain were seen in DH, adenosis and normal tubules/ductules with substantially less intraparenchymal staining in ADH.
Conclusions: IPX is an adequate stain with minimal background interference and high specificity in breast tissue. It can be used in diagnose of breast carcinomas with the advantage of simultaneously testing of multiple markers on one tissue section, which allows conservation of valuable tissue of limited biopsy for prognostic/predictive marker testing. It is advantageous in identify small foci of tumor and aid in definitive diagnosis of microinvasion.
Category: Breast

Wednesday, March 11, 2009 1:00 PM

Poster Session VI # 25, Wednesday Afternoon