A case of an intracystic adenomyoepithelioma of the breast mimicking intracystic carcinoma is described. Preoperative examination with mammography, sonography, computed tomography, and magnetic resonance imaging showed an intracystic tumor with an indistinct margin and several swollen lymph nodes in the ipsilateral axilla. Because the results of fine-needle aspiration cytology of the tumor were interpreted as carcinoma, partial mastectomy with dissection of the axillary nodes was performed. Histopathologic and immunohistochemical examination revealed an intracystic adenomyoepithelioma without nodal involvement. The imaging features of this rare tumor may vary widely, which may result in an incorrect diagnosis of breast carcinoma. Indeed, adenomyoepithelioma has metastatic potential; however, lymphatic spread is rare and axillary intervention may be over-treatment for most cases. While the imaging descriptions of intracystic adenomyoepitheliomas are very limited, this tumor should be considered in the differential diagnosis to avoid unnecessarily aggressive treatment.
2007 by The Japanese Breast Cancer Society