Triple-Negative Breast Cancer: Radiologic-Pathologic Correlation.

Triple-negative breast cancers (TNBCs) are invasive carcinomas that lack ER and PR expression and also lack amplification or overexpression of HER2. Triple-negative breast cancers are histopathologically diverse, with the majority classified as invasive breast carcinomas of no special type with a basal-like profile. Triple-negative breast cancer is the most aggressive molecular subtype of invasive breast carcinoma, with the highest rates of stage-matched mortality and regional recurrence. Triple-negative breast cancer has a younger median age of diagnosis than other molecular subtypes and is disproportionately diagnosed in Black women and BRCA1 germline pathogenic mutation carriers. On US and mammography, TNBCs are most often seen as a noncircumscribed mass without calcifications; TNBCs can have circumscribed margins and mimic a cyst or have probably benign features that may result in delayed diagnosis. MRI is the most sensitive modality for detecting TNBC, with rim enhancement being a common feature, and MRI is also the most accurate imaging for assessing neoadjuvant chemotherapy response. Understanding the radiologic and pathologic findings of TNBC can aid in diagnosis.