Adenomyoepithelioma of the breast with associated atypical lobular hyperplasia: A previously unrecognized association with management implications

Adenomyoepitheliomas of breast are rare tumors. We report for the first time a case of an adenomyoepithelioma of the breast with associated lobular neoplasia. A 53-year-old woman had an annual screening mammogram, which identified areas of asymmetry in her left breast at 4-5-o'clock position. Resection of the masses revealed a well-circumscribed, gray-white, firm discrete nodule (0.8 × 0.4 × 0.3 cm). The tumor was composed of both adenomyoepithelial cell hyperplasia and focal atypical lobular hyperplasia. The 2 cell populations had some overlapping histologic features. Immunohistochemical analysis demonstrated a biphasic proliferation with approximately equal parts of luminal epithelial cells with clear and rounded appearance and myoepithelial cells. The myoepithelial component of the proliferation expressed myosin, p63, CK5/6, S-100, and dimly expressed E-cadherin. The epithelial component of the proliferation strongly expressed E-cadherin. In the areas of atypical lobular hyperplasia, there was distinct loss E-cadherin expression. Awareness of this association is highly important to provide these patients adequate follow-up and treatment.