Email updates

Keep up to date with the latest news and content from Diagnostic Pathology and BioMed Central.

Open Access Highly Accessed Case Report

Invasive lobular carcinoma with extracellular mucin production and HER-2 overexpression: a case report and further case studies

Jing Yu*, Rohit Bhargava and David J Dabbs

Author Affiliations

Department of Pathology, Magee-Womens Hospital of University of Pittsburgh Medical Center, Pittsburgh, PA, USA

For all author emails, please log on.

Diagnostic Pathology 2010, 5:36  doi:10.1186/1746-1596-5-36

Published: 15 June 2010

Abstract

Invasive lobular carcinomas (ILC) of breast typically demonstrate intracytoplasmic mucin. We present a unique case of classical type ILC with abundant extracellular mucin and strong ERBB2 (HER2/neu) expression confirmed by immunohistochemistry and fluorescent in situ hybridization. Dual E-cadherin/p120 immunohistochemical stain demonstrated complete loss of membranous E-cadherin and the presence of diffuse cytoplasmic p120 staining, confirming the lobular phenotype. The tumor cells showed ductal-like cytoplasmic MUC1 staining, but were negative for MUC2 and other mucin gene markers. In addition, studies of tissue microarrays of 80 breast carcinomas with mucinous differentiation revealed 4 pure mucinous carcinomas showing significantly reduced E-cadherin staining without redistribution of p120 into cytoplasm. The findings suggest that the presence of extracellular mucin does not exclude a diagnosis of lobular carcinoma, and the morphologic and molecular characteristics of lobular and ductal carcinomas are more complex than previously appreciated.