Background: There are few data regarding the biological characteristics of apocrine breast carcinoma in the literature due to its rarity and controversy over its definition. We analyzed the histopathological characteristics and tumor biology of apocrine breast carcinomas with regard to histological grade, p53, HER2, bcl-2, MIB-1 and hormone receptor status.
Patients and methods: A consecutive series of 24 female apocrine breast carcinoma patients were the primary source of these retrospective data. Background factors including histological grade, nodal status and lymphatic invasion by tumor cells were analyzed. Immunohistochemical staining for p53, HER2, MIB-1, bcl-2, estrogen receptor (ER) and progesterone receptor (PR) was carried out on formalin-fixed, paraffin embedded specimens.
Results: Older age and postmenopausal status were observed more frequently in patients with apocrine breast carcinoma than those with invasive ductal carcinoma. Apocrine breast carcinoma also showed relatively lower histological grade than invasive ductal carcinoma. Nuclear accumulation of p53, HER2 overexpression, bcl-2 and MIB-1 index were observed in 29% (7/24), 33%(8/24), 25%(6/24) and 29% (7/24) of cases, respectively. Positivity for ER and PR was present in 17% (4/24) and 17% (4/24) of cases, respectively.
Conclusions: Apocrine breast carcinoma tended to show low MIB-1 index, low bcl-2 expression and low positive rate of hormone receptors. There was no correlation between the three types of apocrine carcinoma and the positivity rate of p53, HER2, bcl-2, MIB-1 and hormone receptor status.