Metaplastic Breast Carcinoma With Multiple Muscle Metastasis

Metaplastic breast carcinoma (MBC) is a rare type of breast carcinoma. Recurrence presenting as chest wall invasion is common but rarely as metastasis to distal skeletal muscle in which most patients present with a painful mass. Herein, we report a rare case of 65-year-old woman, with MBC and recurrence presenting as distal multiple muscle metastasis. The patient received surgical excision for symptomatic relief. Unfortunately, she died 12 months postoperatively due to disease progression with multiple lung metastasis. In addition to radiotherapy and chemotherapy, surgical excision is an alternative option in selected patients such as those with painful, isolated, and easily approachable mass. (Medicine 94(17):e662) Abbreviations: CK = cytokeratin, ER = estrogen receptor, Her-2/ Neu = human epidermal growth factor receptor 2, MBC = metaplastic breast carcinoma, MMM = multiple muscle metastasis, MRM = modified radical mastectomy, PET/CT = positron emission tomography/computed tomography, PR = progesterone receptor. INTRODUCTION M etaplastic breast carcinoma (MBC) is rare with an incidence less than 1% of all breast malignancies. It denotes tumors with mixed primary epithelial and sarcomatous components as well as mixed adenocarcinoma with squamous cell carcinoma and tends to be larger in size when diagnosed, with dgar Sy, MD, Hun D, PhD, , MD, Dr. Med reported in 12%, 9%, and 15%, respectively, of patients with MBC. Metastasis commonly occurs to distant organs rather than axillary lymph nodes. The rare incidence of muscular metastasis in all malignancy, as in breast carcinoma, has been reported to range from 0.2% to 17.5% in large autopsy series. Surgical excision was recommended in selected patients such as those with painful, isolated, easily approachable mass. Herein, we report a rare case of MBC with multiple muscle metastasis (MMM). CASE REPORT A 65-year-old Taiwanese woman had a history of debulking surgery, bilateral oophorectomy with omentectomy, total anterior hysterectomy with radical pelvic lymph nodes dissection due to ovarian carcinoma (mucinous-type carcinoma, stage Ic) 1 year ago. Patient’s medical compliance was poor and failed to complete her chemotherapy (cyclophosphamide 750 mg/m, carboplatin 300 mg/m). Recently, she noted a palpable right breast mass, which enlarged rapidly to about 15 cm in size and nearly occupied the whole right breast in 2 months. Core needle biopsy revealed metaplastic carcinoma. Neoadjuvant chemotherapy with the regimens of Taxotere (75 mg/m), Epirubicin (75 mg/m), and Cyclophosphamide (500 mg/m) was given for 6 cycles with poor response, followed by a modified radical mastectomy (MRM) with dissection of axillary lymph nodes and skin grafting. Postoperatively, radiotherapy was done with 5000 cGy in 25 fractions. The histopathologic examination revealed a metaplastic carcinoma with myoepithelial and squamous differentiation associated with adenomyoepithelioma (Figure 1A–C). Immunohistochemistry study showed that the tumor cells are positive for epithelial markers–cytokeratin (AE1/AE3) stain, and myoepithelial markers, including cytokeratin 5/6 (CK 5/6), p63, and S100 stains (Figure 2A–E). Expressions of hormone receptors, including ER, PR, and Her2/Neu, were all negative (Figure 3A–D). The dissected axillary lymph nodes showed metastastic carcinoma with hormone triple-negative in 3 out of 26 nodes. The patient was staged as pT3N1aM0, with histologic tumor grade III. Seven months later, the patient complained about pain and numbness over left forearm, right lower back, and bilateral lower extremities. Fentanyl patch (2.5 mg/q72h) was used for pain control. Sonography of left forearm revealed a tumor with hypervascularity and cystic component, measuring about 6 5 cm in size. Positron emission tomography/computed tomography (PET/C) scan showed hypermetabolic masses in the left proximal forearm, right psoas, and quadratus lumborum muscles (Figure 4). Surgical excision of left forearm mass ed for symptomatic relief of intractable on for the right psoas and quadratus ion was not feasible due to high risks www.md-journal.com | 1