[165] WT1 Immunohistochemistry as a Novel Marker for Breast Myoepithelial Cells

Mohiedean Ghofrani, Ozlen Saglam, Fattaneh A Tavassoli. PeaceHealth Laboratories, Vancouver, WA; Yale University, New Haven, CT

Background: The Wilms tumor-1 (WT1) gene plays a critical role in urogenital development. Originally reported as the main gene in the development of nephroblastomas, WT1 was later seen in a wide variety of benign and neoplastic tissues by immunohistochemistry (IHC). In breast, WT1 expression has been reported in mucinous carcinomas, invasive micropapillary carcinomas, and carcinomas with basal-like and ERBB2 profiles, as well as a marker of endothelial and myoepithelial differentiation.
Design: Thirty benign and malignant breast tissues were stained to assess WT1 expression in myoepithelial cells. Patients, including 3 males, ranged in age from 15 to 78 years. Breast ducts from normal reduction mammoplasty tissue as well as a variety of benign, precancerous and malignant lesions were evaluated, including adenosis, gynecomastia, fibroadenoma, intraductal papilloma, ductal hyperplasia, ductal intraepithelial neoplasia (atypical ductal hyperplasia and in situ carcinomas of all grades) and invasive carcinoma. Patterns of WT1 expression were evaluated in myoepithelial cells compared to conventional markers such as p63 and calponin.
Results: Breast myoepithelial cells within lobules as well as ducts of all calibers expressed WT1 protein in a diffuse cytoplasmic pattern. Myoepithelial cell nuclei were clearly negative for WT1 protein by IHC. In several cases cytoplasmic staining intensity varied across ducts in the same field, but this heterogeneity seemed to complement the variation in staining for calponin, another cytoplasmic marker of myoepithelial cells.

Conclusions: WT1 IHC may be used as an alternative marker for breast myoepithelial cells in benign and malignant breast lesions. The fact that WT1 protein is expressed in the cytoplasm of breast myoepithelial cells suggests the possibility of pairing WT1 with a nuclear myoepithelial marker such as p63 and/or another complementary cytoplasmic marker such as calponin to develop a more robust IHC panel.

Category: Breast

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 16, Wednesday Morning


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