Male Adenoid Cystic Carcinoma of Breast

[Introduction]Adenoid cystic carcinoma (ACC) of the breast is a rare tumor, especially observed in males.[Case Presentation]We presented a 42-year-old man, initially diagnosed with small cell carcinoma (SCC) by core needle biopsy. He underwent breast modified radical mastectomy (MRM) and axillary lymph node dissection; his final histopathological diagnosis was ACC. After surgery, although the patient was recommended to have post-operative chemo-radiotherapy, he did not comply. The patient is on follow-up for more than a year with no recurrence until now.[Conclusions]ACC of the breast is a rare malignancy with excellent prognosis and favorable tumor biology. It could be mistaken with triple negative breast cancer, ductal carcinoma in situ (DCIC), and small cell carcinoma.