Malignant myoepithelioma of the breast: A case report and review of the literature.

Malignant myoepithelioma of the breast is an extremely rare tumor composed entirely or almost entirely of malignant spindle cells with myoepithelial differentiation. Only a limited number of case reports have been descibed to date; therefore the biological behavior and treatment outcomes of this rare tumor have not been clearly determined. Herein, we present a case of a 74-year-old woman who was admitted with inflammatory-like cancer of the breast, presenting with invasion of the chest wall and axillary lymph node metastasis at the time of diagnosis. The histological examination revealed a tumor composed of epithelioid and spindle cells with moderate to marked nuclear atypia, with foci of hemorrhage and necrosis. The tumor cells were immunoreactive for vimentin, p63, p53, CD10, cytokeratin (CK)8/18, CKAE1-3 and S-100. Finally, a diagnosis of myoepithelial carcinoma of the breast was established. Neoadjuvant chemotherapy was first administered and proved to be ineffective. Due to locoregional progression that was associated with the development of an abscess and subsequent excessive bleeding, a palliative mastectomy was performed. Postoperatively, one more cycle of systemic chemotherapy was administered. However, the patient experienced an early relapse to the chest wall and succumbed to septic shock due to persistent local infection. The aggressiveness and chemoresistance of the tumor in this case was consistent with the existing bibliography.