Acinic cell carcinoma of the breast: review of the literature.

INTRODUCTION: The breast and salivary gland tissue share embryologic and thus pathological similarities. Acinic cell carcinoma (ACC) is a typical tumor in salivary glands, but rarely arises in breast too. We reviewed 38 cases of mammary ACC reported in literature and our case, the first ACC born within a fibroadenoma.

MATERIALS AND METHODS: Data were collected by a research for the key words acinic cell carcinoma breast on Pubmed in March 2014, including a case treated in our department. All reviewed cases were compared for clinical approach and histological pattern.

RESULTS: To date 23 articles presenting cases of ACC of the breast are reported in literature. We included in our review 38 cases previously described and one new case. The histological pattern was predominantly solid with a microglandular structure. All the tumor cells were cytologically characterized by monotonous round cells with a finely granular, weakly eosinophilic, or clearly vacuolated cytoplasm. The most of the cells were intensely stained with anti-lysozime, anti-amylase, anti-α1-chimotripsin, anti-EMA and anti-S100 protein antisera. Immunohistochemistry was also performed to point out: estrogen receptor (ER), progesterone receptor (PR), androgen receptors (AR), human epidermal growth factor receptor 2 overexpression (HER2/neu), E-cadherin (E-cad), cytokeratin-7 (CK7), gross cystic disease fluid protein 15 (GCDFP15), smooth muscle actin (SMA).

CONCLUSION: ACC of the breast is a rare tumor, showing similarities with the salivary gland counterpart, above all in terms of good prognosis, and differences from the ordinary invasive breast carcinoma. Further investigations are needed to elucidate the true histogenesis and the correct treatment.