Malignant Adenomyoepithelioma of the Breast and Responsiveness to Eribulin

Abstract

Adenomyoepithelioma (AME) of the breast is an uncommon tumor characterized by its dual differentiation into luminal cells and myoepithelial cells. In most cases these tumors have a benign clinical course, but distant metastases have been reported. We present the case of a 51-year-old woman diagnosed with malignant AME. The patient underwent a right modified radical mastectomy, and pathological examination confirmed the diagnosis of malignant AME. Ten months after the operation, multiple hepatic, pleural, and abdominal wall metastases were detected. A number of palliative chemotherapeutic agents were tried, including anthracycline and taxanes. However, the disease continued to progress, and superior vena cava syndrome developed as a result of direct tumor invasion. The patient received salvage eribulin monotherapy. After two cycles of this treatment, her clinical symptoms were ameliorated, and a computed tomography scan showed a partial response. Eribulin chemotherapy was thus effective in treating malignant AME in this case.

Keywords: Breast; Eribulin; Malignant adenomyoepithelioma; Neplasm metastasis.

Figure 1. Malignant adenomyoepithelioma of the breast. (A) Biphasic proliferation of both inner eptithelial and outer myoepithelial cells was shown (H&E stain, ×200). (B) Atypia was obvious in both myoepithelial and ductal epithelial cells with moderate degree of nuclear pleomorphism, prominent nucleoli, high nuclear cytoplasmic ratio and increased mitotic figures (H&E stain, ×400). (C) The ductal cells were positive for CK5/6 (immunoperoxidase, ×40). (D) The myoepithelial cells were positive for p63 (immunoperoxidase, ×40). (E) The tumor showed lymphovascular invasion (H&E stain, ×100).

Figure 2. Radiologic findings for chest computed tomography (CT). CT scan showed marked enlarged recurred mass lesion in right mediastinal pleural areas, which invaded to right pulmonary trunk and superior vena cava.

Figure 3. Histological features of metastatic lesion. The abdominal mass showed similar histological findings as in malignant adenomyoepithelioma of the breast (H&E stain, ×20).

Figure 4. Chest computed tomography (CT) after eribulin treatment. After two cycles of eribulin treatment, the follow-up CT scan showed decreased extent of recurred mass lesion in right mediastinal pleural areas.