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Myoepithelial Cell Staining Patterns of Papillary Breast Lesions
From Intraductal Papillomas to Invasive Papillary Carcinomas

Cheryl B. Hill MD, I-Tien Yeh MD
DOI: http://dx.doi.org/10.1309/XG7TPQ16DMJAV8P1 36-44 First published online: 1 January 2005

Abstract

We evaluated 25 intraductal papillomas and 18 papillary carcinomas (invasive, 4; micropapillary ductal carcinoma in situ [DCIS], 5; cases originally classified as intracystic/intraductal papillary carcinoma, 9) by calponin, smooth muscle myosin heavy chain (SMM-HC), and p63 immunostains.

Calponin, SMM-HC, and p63 labeled myoepithelial cells (MECs) in all intraductal papillomas and all micropapillary DCIS cases. The invasive papillary carcinoma cases were uniformly negative for all stains. The 9 cases originally diagnosed as intracystic/intraductal papillary carcinoma showed more variable results, with identification of an MEC layer in only 4 cases. Comparison of staining of MECs by these 3 stains showed that calponin was more sensitive and intense than SMM-HC; however, there was cross-reactivity with myofibroblastic cells. Staining with p63 was discontinuous, making interpretation of an intact myoepithelial layer difficult.

Of 9 cases originally classified as intraductal papillary carcinoma, 5 showed absence of a basal MEC layer by immunohistochemical analysis. The lack of a basal MEC layer in these cases suggests a spectrum of progression from in situ to invasive disease and might help explain distant metastases from previously reported “intraductal papillary carcinoma.”

Key Words:
  • Papillary breast carcinoma
  • Myoepithelial cell
  • Calponin
  • Smooth muscle myosin heavy chain
  • p63