33 Special Types of Invasive Breast Carcinoma: Diagnostic Criteria ...

Basal-like Breast Cancers
• Often display medullary-like features.
• Usually express low levels of ER/PR & lack HER2
over expression or amplification.
• Resemble the myoepithelial-cell phenotype.
• Mi Minority it hharbor b EGFR gene amplification lifi ti or
aneusomy.
• p53 expression or TP53 mutations in up to 85%.
• ~30% of basal-like cancers are pRB-/p16+/p53+.
• Carcinomas in BRCA1 germ-line mutation carriers
are basal-like.
• Some high-grade DCIS lack ER, PR, HER2.
• These DCIS cases express ‘basal’ markers.
• Triple-negative and basal-like cancers often lack
in situ component.
• Less frequently disseminate to LNs & bones.
• Favor hematogenous g spread, p with a pproclivity y for
metastatic deposits to the brain and lungs.
• At present, use of the term “basal-like breast
cancer” in diagnostic surgical pathology
reports does not appear to be justified, as it
does not lead to any direct clinical action.
Other basal-like phenotype cancers are…
• Medullary & atypical medullary carcinoma.
• Metaplastic carcinomas.
• Myoepithelial carcinoma (“metaplastic”).
• Secretory carcinoma.
• Adenoid cystic carcinomas.
10/8/2011
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