Primary acinic cell carcinoma of the breast: A case report and review of literature.

Background: In the current World Health Organization classification, acinic cell carcinoma (AcCC) of the breast is considered a rare histological subtype of triple-negative breast cancer. Because of the few reports in the literature, data concerning clinical outcomes are limited. Here, we report a case of AcCC of the breast in a 48-year-old woman.

Case Summary: A 48-year-old woman with a mass in her right breast came to our hospital for further diagnosis. Mammography and an ultrasound (US) scan showed a mass in the upper inner side of the right breast. She then underwent surgery to resect the mass in her right breast. Postoperative pathological examination revealed that the tumor had abundant acinar-like structures formed by tumor cells with prominent eosinophilic granules in the cytoplasm, consistent with acinar cell carcinoma. The results of immunohistochemical analysis supported the diagnosis of breast acinar cell carcinoma. Two months later, she underwent breast-conserving surgery and sentinel lymph node biopsy. The pTNM stage was T2N0M0. After surgery, the patient received 30 radiotherapy sessions. The patient was followed up for a period of one year, and no recurrence was found.

Conclusion: AcCC of the breast is a rare type of malignant tumor. Because it is usually asymptomatic and can be detected by imaging studies, routine breast US or mammograms are important. However, there are no characteristic diagnostic imaging findings or clinical manifestations, so immunohistochemical examination is critical for an accurate diagnosis of AcCC of the breast.