Abstract
BackgroundBreast carcinomas can be classified into five subtypes based on gene expression profiling or immunohistochemical characteristics. Among these subtypes, basal-like breast carcinomas (BLBCs) are one of the most studied group, due to their poor prognosis. The aim of this study was to investigate the prevalance, morphological and immunohistochemical features of BLBCs, in Turkish population.MethodsFive hundred invasive breast carcinomas were reviewed for several morphological features and immunostained for oestrogen and progesterone receptors, c-ERB-B2, cytokeratin5/6, cytokeratin14, vimentin and epidermal growth factor receptor (EGFR). Basal-like breast carcinoma was defined as a triple negative tumor with cytokeratin5/6 and/or EGFR positive.ResultsThe prevalance of BLBC was 9.6%. All medullary carcinomas and 55.6% of metaplastic carcinomas showed basal-like immunophenotype. Patients with BLBC were younger (p=0.04) and had higher-grade tumors (p<0.0001). Morphologic features associated with BLBC included increased mitosis, nuclear pleomorphism, presence of geographic and/or central necrosis, pushing margin of invasion and stromal lymphocytic response (p<0.0001). Presence of prominent nucleoli and vesicular nuclear chromatin were the cytological features correlated with basal-like phenotype (p<0.0001). On multivariate analyses, BLBCs were associated with high mitotic number (p<0.0001), the presence of vesicular chromatin (p=0.004), high tubular grade (p=0.011), lymphocytic response (p=0.031) and the absence of carcinoma insitu (p=0.039). Vimentin was positive in 53.2% of BLBCs, while cytokeratin14 was less frequently expressed (27.7%).ConclusionsBLBCs have some distinctive, but not pathognomonical, morphological features. Paying attention to these features and adding cytokeratin14 and vimentin to the immunohistochemical panel can help the definitive diagnosis of BLBCs.Virtual slideHttp://www.diagnosticpathology.diagnomx.eu/vs/5962175467857400
Highlights
Breast carcinomas can be classified into five subtypes based on gene expression profiling or immunohistochemical characteristics
There are 19 subtypes of breast carcinoma according to World Health Organization (WHO) 2003
The aim of this study is to determine the incidence of Basal-like breast carcinoma (BLBC) and to define their morphological and immunohistochemical features by comparing them with the other types of breast carcinomas
Summary
Breast carcinomas can be classified into five subtypes based on gene expression profiling or immunohistochemical characteristics. Among these subtypes, basal-like breast carcinomas (BLBCs) are one of the most studied group, due to their poor prognosis. The BLBCs constitute approximately 15% of invasive breast cancers [6]. These tumors occur frequently in premenopausal young patients [7]. They are associated with larger tumor size and distinctive histological features, including high histological grade with high mitotic rate and nuclear/cytoplasmic ratio, the presence of spindle cell or squamous metaplasia, pushing growth pattern, central acellular areas of hyalinization or necrosis and lymphocytic infiltrate [7,8,9,10]. Medullary and atypical medullary carcinomas, myoepithelial carcinomas and metaplastic carcinomas may show the phenotype of basal-like carcinomas [8]
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