basal-like invasive ductal carcinoma

Definition: BLIDC are not rigidly defined, usually positive for CK5/6, CK14 or CK17, and triple negative (ER-, PR-, HER2-), often positive for EGFR. Original definition based on gene expression profile (Nature 2000;406:747, Proc Natl Acad Sci USA 2001;98:10869). These tumors are clinically heterogeneous.

BLIDC is generally considered to not be comparable to triple negative tumors by immunostains (Clin Cancer Res 2008;14:1368, Med Mol Morphol 2009;42:128) but see Breast Cancer Res 2007;9:R65).

Classification of particular tumors may vary based on which classification system is used (Hum Pathol 2008;39:506).“Basal like” because tumors have high expression of genes characteristic of basal epithelial cells of normal mammary gland, including CK 5/6, CK14, CK15 and CK17. It is not validated bu the WHO system of tumor classification.