Adenomyoepithelioma of the Breast in the Setting of Prior Contralateral Breast Malignancy.

An 81-year-old female patient underwent a screening mammogram one year after completing treatment for right-sided estrogen receptor (ER)/progesterone receptor (PR)-negative ductal carcinoma in situ (DCIS). A new 1-cm mass was noted in the contralateral breast. Ultrasound and percutaneous core needle biopsy results were suggestive of an atypical papillary lesion. An excisional biopsy was performed, and the final pathology was consistent with a benign adenomyoepithelioma (AME). Surgical resection was considered her definitive treatment. AME of the breast is a rare clinical entity, with only a handful of case reports and case series available. In this case report, we review common clinical and radiologic presentations, methods of diagnosis, and recommendations for management based on current literature. The presence of an AME in the background of a previous or synchronous breast malignancy occurs in a very small percentage of cases. On review of available literature, we identified other cases with a past or current history of breast malignancy.