Malignant adenomyoepithelioma of the breast with contralateral homologous tumor and ductal carcinoma in situ: two case reports.

INTRODUCTION AND IMPORTANCE: Malignant adenomyoepithelioma (MAME) is a rare biphasic breast tumor with no standardized management guidelines. Co-occurrence with other breast malignancies is extremely rare. CASE INTRODUCTION: We report two cases with long-term follow-up: a 59-year-old female with left invasive MAME and contralateral intermediate-grade ductal carcinoma in situ, and a 62-year-old female with bilateral MAME. Both underwent bilateral mastectomy with sentinel lymph node biopsy (SLNB). CLINICAL DISCUSSION: MAME may co-occur with homologous or breast malignancies of ductal origin, suggesting a possible association that requires validation in larger studies. There is no consensus on adjuvant therapy. Both cases had negative SLNBs, highlighting the need to optimize axillary management. Molecular research is needed to develop targeted therapies. CONCLUSION: MAME has nonspecific clinical features. Our preliminary observations suggest a possible association with concurrent breast malignancy that requires further validation.