Case report: Metastatic metaplastic breast cancer with choriocarinomatous features: Targeting the choriocarcinoma component for cure.

Breast cancer with choriocarcinomatous features (BCCF) is a rare and aggressive breast cancer. BCCF carries a poor prognosis and there is unfortunately scant literature to guide treatment beyond surgical resection with most patients receiving standard regimens for breast cancer. In our case, we present a 42-year-old female with an initial hCG of 2,324 and two suspicious lesions of the right breast. On biopsy, each lesion had distinct histopathology with the larger lesion diagnosed as BCCF and the smaller lesion being an invasive ER/PR positive ductal carcinoma. The diagnosis of BCCF rather than metastatic choriocarcinoma was confirmed using DNA typing. Salvage chemotherapy targeting choriocarcinoma resulted in marked clinical and biomarker success including normalization of the hCG. After recurrent brain metastases were diagnosed, high dose chemotherapy with methotrexate was administered resulting in long term remission.