Metaplastic breast carcinoma composed of epithelial–myoepithelial carcinoma and squamous cell carcinoma: A case report

RATIONALE: Metaplastic breast carcinomas are a group of breast malignancies with varying histomorphological characteristics and prognoses. The tumor composed of epithelial -myoepithelial carcinoma and squamous cell carcinoma was not reported previously. PATIENT CONCERNS: An 81-year-old woman presented with a palpable nodule in the left breast for 4 days. The ultrasonography showed multinodular growth and focally indistinct borders. Owing to her advanced age and possible early clinical staging, primary tumor resection was performed. One year later, a small and slow growing subcutaneous nodule was found under the incision of the left breast. Ultrasonography revealed an irregular, cystic and solid, hypoechoic mass with circumscribed borders. DIAGNOSES: Microscopic examination of the primary tumor revealed epithelial -myoepithelial carcinoma and squamous cell carcinoma. The former had a variety of architecture patterns, including nests, lobulations, papillary and tubular structures, and the latter showed varying morphological features, from squamous pearls to spindle cells. The recurrent tumor showed only epithelial -myoepithelial carcinoma with more aggressively malignant features than those seen in the primary tumor. INTERVENTIONS: An extensive resection of the left breast mass was performed for the recurrent tumor. The patient did not receive any adjuvant chemotherapy or radiation therapy because of the patient's advanced age. OUTCOMES: The patient has been followed up for 1.5 years after second surgery without evidence of tumor recurrence and metastasis. LESSONS: Wide local excision with adequate margins is recommended for elderly patients with metaplastic breast carcinoma composed of epithelial -myoepithelial carcinoma and squamous cell carcinoma.