Most Salivary Gland-Like Tumors of Breast Express Basal Type Immunohistochemical Markers
C Reyes, M Jorda, A Mejias, C Gomez-Fernandez. University of Miami Jackson Memorial Hospital and Sylvester Comprehensive Cancer Center, Miami, FL
Background: Salivary gland-like tumors represent approximately 2% of primary breast carcinomas. These special histologic subtypes are characteristically negative for ER, PR, and HER2 (triple-negative) and include adenoid cystic carcinoma, mucoepidermoid carcinoma, acinic cell carcinoma, and polymorphous low-grade adenocarcinoma . Approximately 75% of triple-negative breast carcinomas belong to the basal-like subtype by gene expression profiling. Immunohistochemical panels that include basal-like markers such as EGFR, CK5/6, p-cadherin, p63 and c-kit provide useful surrogates to gene expression arrays for classification of triple-negative breast cancers into the basal-like subtype. The purpose of this study was to explore the expression of these markers in salivary gland-like tumors of the breast.
Design: Excisional specimens from 10 untreated invasive triple-negative mammary carcinomas with salivary gland-like morphologies were evaluated for the immunohistochemical expression of EGFR, CK5/6, p-cadherin, p63 and c-kit using formalin-fixed, paraffin-embedded tissue and the L-SAB detection method.
Results: Based on morphology, 4 carcinomas were classified as adenoid cystic, 3 as mucoepidermoid, 2 as polymorphous low-grade and 1 as acinic cell. All of the adenoid cystic carcinomas, mucoepidermoid carcinomas and polymorphous low grade adenocarcinomas showed strong and diffuse expression of CK5/6, EGFR, p-cadherin, p63, and c-kit. The single case of acinic cell carcinoma expressed c-kit, but failed to express the other basal-like immunohistochemical markers.
Conclusions: Adenoid cystic, mucoepidermoid and polymorphous low-grade carcinomas of the breast express immunohistochemical markers that characterize the intrinsic basal-like subtype of breast cancer.
Monday, March 22, 2010 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 32, Monday Morning