Abstract
Adenomyoepithelioma of the breast is a rare breast neoplasm and has basically been considered to be a benign tumor. However, we have sometimes encounter case reports of malignant adenomyoepithelioma in the literature recently. In this paper, we present a case of adenomyoepithelioma of the breast associated with invasive ductal carcinoma. The case involved an 85-year-old woman who was seen at the hospital because she was aware of a tumor in the outer upper quadrant of the left breast. Ultrasonography showed a 1.4-cm diameter hypoechoic tumor which had a smooth and well-defined margin and a lobulated appearance. Fine needle biopsy cytology provided a diagnosis of invasive ductal carcinoma of the breast. Wide excision of the left breast and left axillary lymph node dissection were performed with the diagnosis of stage I breast cancer. Histopathology showed proliferation of both glandular epithelial and myoepithelial cellular elements, keeping a bi-phasic fashion. On immunohistochemistry, the glandular epitherium was EMA positive and myoepitherium was αSMA positive, adenomyoepithelioma being diagnosed. In addition a 2.3-mm diameter papillotubular carcinoma was identified in an extremely limited area at the tumor margin. The adenomyoepithelioma cells were lowly atypical, no mitotic figure was noted, and no findings suggestive of transition with adenomyoepithelioma were observed. Accordingly these neoplasms appear to have occurred independently and clashed with each other.
