[A Case of Primary Acinic Cell Carcinoma(ACC)of the Breast].

A49 -year-old woman presented with a 3.5 cm mass in her right breast. Mammography revealed a lobular mass with poorly defined margins and no microcalcification. Ultrasonography showed a hypoechoic mass with an irregular margin. The tumor was diagnosed as breast carcinoma using a core needle biopsy. The patient underwent a modified radical mastectomy with sentinel lymph node biopsy, and received adjuvant chemotherapy. The tumor consisted of 2 types of carcinoma. The center of the tumor was solid-tubular carcinoma, and the periphery was acinic cell carcinoma(ACC). Histopathologically, the neoplastic cells of the periphery were characterized by widespread acinic cell-like differentiation with a eosinophilic granular or clear cytoplasm, resembling acinic cells of the parotid gland(t3, f[+], ly0, v0, n0, stage II B). Immunohistochemically, the specimens tested positive for salivary gland amylase, and negative for collagen type IV , ER, PgR, and HER2. We administered UFT as adjuvant chemotherapy. Eight months after surgery, local recurrence was observed. ACC of the breast is rare, and has been reported to have a good prognosis. Further investigations are needed to elucidate its true histogenesis the appropriate treatment.