Atypical Adenomyoepithelioma of the Breast: A Diagnostic Dilemma

Adenomyoepithelioma (AME) of the breast is a rare lesion characterized by a biphasic proliferation of epithelial cells and myoepithelial cells. AME is a spectrum of disease ranging from purely benign, atypical lesions with low/uncertain malignant potential to frankly malignant with distant metastasis. Although atypical adenomyoepthieliomas typically follow a benign course, current publication suggest that it exhibits the potential for local recurrence even after negative initial margins and can undergo malignant transformation into a high-grade carcinoma.1 The imaging and core needle biopsy findings of an atypical adenomyoepithelioma can be difficult to differentiate from benign lesions or even invasive carcinoma. A definitive diagnosis requires an excisional biopsy with immunohistochemistry for thorough pathological review. Surgical excision with wide and clear margins is the recommended treatment for atypical AMEs. Close long-term follow-up is necessary to monitor any local or distant recurrence. We present a case of an atypical adenomyoepithelioma of the breast and discuss the diagnostic challenges and the multidisciplinary management associated with this unusual lesion.