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Breast malignant, males, children

Carcinoma subtypes

Luminal phenotype


Reviewer: Monika Roychowdhury, M.D., (see Reviewers page)
Revised: 15 November 2012, last major update August 2012
Copyright: (c) 2001-2012, PathologyOutlines.com, Inc.

General
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● Defining molecular feature is ER expression
● Major difference between luminal A and luminal B breast cancers is degree of proliferation and HER2 expression signature, which is more pronounced in luminal B (Breast Care (Basel) 2011;6:258)

Terminology
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● Not part of current WHO breast classification

Clinical features
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● Classification is based on gene expression (molecular) profile studies; subtype reflects clustering of genes activated by ER signaling pathways
● Distribution by molecular typing is: luminal A: 71%; luminal B: 8%; HER2+: 6%; basal-like: 15% (Ann Surg Oncol 2009;16:2705)
● Luminal subtypes include luminal A (ER+ [strong], PR+, HER2-) and luminal B (ER+ [weak/moderate], PR-, sometimes HER2+)
● Some authors also include categories of luminal A-HER2 and luminal B-HER2 hybrids (Int J Clin Exp Pathol 2009;2:444)
● Luminal cytokeratins are CK7/8, 18 and 19
● Luminal A and B subtypes are associated with mutations in E-cadherin and MAP2K4, and amplifications of Cyclin D1, HER2 and HDM2 (Breast Cancer Res Treat 2010;121:53)
● Luminal A breast cancers are usually low grade, with slow growth and better prognosis than luminal B (J Natl Cancer Inst 2009;101:736)
● Luminal B breast cancers: some are HER2+, but the major biological distinction from Luminal A is the proliferation signature, in which CCNB1, MKI67 and MYBL2 genes have higher expression in luminal B than in luminal A tumors (BMC Genomics 2006 Apr 27;7:96)
● Luminal A and most grade 1 luminal B (HER2+) cases are low proliferative (Breast Cancer 2012 Mar 31 [Epub ahead of print])

Micro images
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Classic Luminal A tumor is ER+ (strong), Ki-67 low


Uncommonly, Luminal A tumor has high Ki-67 index

Various images

Positive stains
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● CK7, CK8/18, ER

Additional references
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Clin Exp Metastasis 2012;29:493, Oncology 2011;81:336

End of Breast malignant, males, children > Carcinoma subtypes > Luminal phenotype


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