Secretory carcinoma of the breast: a tumour analogous to salivary gland acinic cell carcinoma?

Aims: Acinic cell-like breast carcinoma is a newly recognized entity, and few acinic cell-like breast carcinoma cases have been reported. All reported acinic cell-like breast carcinomas were counterparts of the solid type of acinic cell carcinoma of the salivary gland. We report here three cases of secretory breast carcinoma with acinic cell differentiation, and discuss the similarity between secretory breast carcinoma and acinic cell carcinoma of the salivary gland. Methods and results: The cases were histologically identical to acinic cell carcinoma of the salivary gland: papillary-cystic type in case 1, a mixture of papillary-cystic, microcystic and follicular type in case 2, and microfollicular type in case 3. Immunohistochemically, the tumour cells were positive for salivary-type amylase, lysozyme, S100 protein and alpha(1)-antitrypsin, and negative or less reactive for gross cystic disease fluid protein-15 and oestrogen receptor. All three cases did not reveal metastasis or recurrence. Conclusions: These cases were typical of secretory breast carcinoma, and were clinically, histologically and immunohistochemically analogous to acinic cell carcinoma of the salivary gland. We emphasize that secretory breast carcinoma and acinic cell carcinoma of the salivary gland may be identical lesions.