ERBB2 and triple-negative breast carcinoma: Triple negative breast carcinomas (TNBC) are defined by absence of expression for estrogen receptor (ER) and progesterone receptor (PR) by immunohistochemistry (IHC), absence of overexpression for human epidermal growth factor receptor HER2/neu (HER2) by IHC, and absence of amplification of HER2 by fluorescent in situ hybridization (FISH).