Case Report Axillary Metaplastic Breast Carcinoma with Ipsilateral Pectoral Invasive Ductal Carcinoma: An Unusual Presentation Lei Zhang, 1,2 Sabahattin Comertpay, 3 David Shimizu, 1 Richard M. DeMay, 4 Michele Carbone, 1,3 Stacey A. Honda, 1 and Jodi M. Matsuura Eaves 1 1 Department of Pathology, University of Hawaii, 651 Ilalo Street, No. 411E, Honolulu, HI 96813, USA 2 Mercy Hospitals at Bakersfield, 2215 Truxtun Avenue, Bakersfield, CA 93301, USA 3 Cancer Center of Hawaii, 2226 Liliha Street, Honolulu, HI 96817, USA 4 Department of Pathology, University of Chicago, 5841 South Maryland Avenue MARP 212, MC 2050, Chicago, IL 60637, USA Correspondence should be addressed to Lei Zhang; lei 248@hotmail.com and Jodi M. Matsuura Eaves; jodi.m.matsuura-eaves@kp.org Received 22 June 2014; Accepted 6 September 2014; Published 16 September 2014 Academic Editor: Ossama W. Tawfk Copyright © 2014 Lei Zhang et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We report a case of axillary metaplastic breast carcinoma (MBC) with triple negative (ER−/PR−/Her2−) phenotype, concurrent with multifocal invasive ductal carcinoma (IDC) of ipsilateral pectoral breast (ER+/PR+/Her2−) in a 60-year-old woman. Te two tumors demonstrate diferent morphology, immunophenotype, and opposite response to neoadjuvant chemotherapy of paclitaxol, adriamycin, and cyclophosphamide. Methylation analysis of human androgen receptor (HUMARA) on X-chromosome identifed monoclonal pattern of X-chromosome inactivation in MBC and mosaic pattern in the IDC. Stem cell origin of MBC is suggested in this case. Clinicopathological features, imaging fndings, biological markers, chemoradiation management, and prognosis of MBC are reviewed in comparison to invasive ductal carcinoma. Our case and literature review suggest that traditional chemotherapy applicable to IDC is less efective towards MBC. However, new chemotherapy protocols targeting stem cell and multimodality management of MBC are promising. Recognition of unusual presentation of MBC will help tailor therapy towards tumor with worse prognosis. 1. Introduction Metaplastic breast carcinoma (MBC) constitutes 0.2–1% of all breast cancer diagnoses [1, 2]. Axillary MBC has not been described. We present a rare case of ipsilateral synchronous MBC in the axillar with concurrent multifocal invasive ductal carcinoma (IDC) of pectoral breast and discuss clinicopatho- logical and management diferences of these two tumors. 2. Case Presentation 2.1. Clinical Presentation. A 60-year-old female with no fam- ily history of malignancy presented with a lef breast mass and lef axillary enlargement. Computed tomography (CT) and magnetic resonance imaging (MRI) of the chest showed two masses in the lef breast: one at 9 o’clock, 1cm from nipple and 3.4cm in size, and the other at 2 o’clock, 7cm from nipple and 1.6 cm in size. A lef axilla mass measuring 5.4 cm with smooth border suspicious for lymph node was also identifed. CT of the chest and abdomen showed no other metastases. Te 9 o’clock lesion was biopsied and the patient was treated with 12 cycles of Taxol and 4 cycles of adriamycin and cyclophosphamide. Te medial and lateral lesions of lef breast both shrank, but the axillar mass enlarged. Modifed radical mastectomy and axillary dissection were performed at the earliest possible time. Shortly afer the surgery, lung and brain metastases were identifed and the patient elected to hospice discharge and subsided afer 10 months. 2.2. Pathological Findings. Biopsy of the 9 o’clock breast lesion showed invasive ductal carcinoma (Figure 1(a)), positive for estrogen receptor (ER, 100%) and progesterone receptor Hindawi Publishing Corporation Case Reports in Oncological Medicine Volume 2014, Article ID 938509, 6 pages http://dx.doi.org/10.1155/2014/938509