Rare imaging appearance of adenoid cystic carcinoma of the breast: A case report.

Adenoid cystic carcinoma (ACC) of the breast is a rare tumor comprising <0.1% of all breast malignancies. The present study reports the case of a 66-year-old woman who underwent multiple imaging techniques, including mammography, ultrasonography and magnetic resonance imaging (MRI). The patient reported gradual enlargement of a mass in the left breast. Mammography identified a high-density, irregular mass, with nipple retraction. Ultrasonography revealed an irregular, complex cystic and solid mass with an unclear margin in the subareolar region. The internal vascularity was seen on Doppler examination. The lesion on MRI was also mixed cystic and solid, with an irregular shape and irregular margins. The solid part of the lesion appeared heterogeneously isointense on T1-weighted imaging (WI) and a slightly high signal on T2WI, and exhibited internal septations with a low signal on T2WI. Following injection of contrast agent, the enhancement of the solid part was rapid and heterogeneous. The cystic parts of lesion appeared as high-signal on T1WI and T2WI. The tumor infiltrated the left nipple and adjacent skin. The patient underwent a left modified radical mastectomy with axillary lymph node dissection. The pathological examination confirmed the tumor as ACC of the left breast. The axillary lymph nodes were negative for tumor metastasis. Therefore, the differential diagnosis of mixed cystic and solid breast masses with unclear margins and internal septations on T2WI exhibiting delayed enhancement, must include ACC.