Adenomyoepithelioma of the breast: a brief diagnostic review.

Adenomyoepithelioma of the breast is an uncommon tumor characterized by dual differentiation into luminal cells and myoepithelial cells. A spectrum of histologic patterns is observed among these tumors and even in different areas of individual tumors. These lesions can be diagnostically challenging, especially when a core needle biopsy is performed, because of the heterogeneity of adenomyoepitheliomas. Recognition of the biphasic cellular elements and the characteristic overall architecture of the tumors in combination with immunohistochemistry are essential to establish the correct diagnosis. Although most tumors have a benign clinical course, local recurrences, malignant transformations, and distant metastases have been reported. All the reported malignant adenomyoepitheliomas with metastases have shown significant cytologic atypia and brisk mitotic rates. Therefore, adequate sampling of the tumor to identify these features is necessary. A complete excision with adequate margins would lower the chance of local recurrence or potential for metastasis.