Apocrine lesions of breast and invasive carcinoma with apocrine differentiation: a brief review

Summary Apocrine metaplastic change is a frequent change in breast pathology. Invasive carcinoma with apocrine differentiation of the breast has unconventional histology, immunohistochemical (IHC), and molecular profile. It has an Estrogen receptor (ER)/Progesterone receptor (PR) negative and an Androgen receptor (AR) positive profile. About 1/3 of cases can show Her2neu amplification through IHC or Fluorescence in situ hybridization (FISH). Lymphovascular invasion (LVI) and lymph node metastasis (LNM) are frequently observed and they often have poor pathological response to chemotherapy. Histologically and molecularly defined apocrine subtypes of breast cancer, although have considerable overlap, yet are different and discrete entities. The decision on using chemotherapy and targeted regimens in these lesions is still controversial which calls for more insight. This could be achieved by acquiring a standardized diagnostic practice, further research, and discussion.