Breast invasive carcinoma with a choriocarcinomatous pattern

A 36-year old female was diagnosed with a breast infiltrating duct carcinoma, NOS, G2, luminal B HER2-neg, metastatic to the lymph nodes, lungs, liver and bones. She received ribociclib, fulvestrant and LHRH analog for 15 months with partial remission. For personal reasons the patient interrupted therapy for 4 months, but reported afterwards due to rapid progression. A core-biopsy revealed no presence of usual infiltrating duct carcinoma, but unequivocal choriocarcinoma-tous differentiation with mononuclear cytotrophoblast-like cells with hyperchromatic nuclei and multinucleated syncy-tiotrophoblast-like giant cells (fig. 1) and strong cytoplasmatic immunoreactivity for β-HCG (fig. 2). Pathologist suggested either a rare variant of invasive breast carcinoma with a cho-riocarcinomatous pattern or metastatic choriocarcinoma to the breast. Metastatic progression was seen; pregnancy, as well as primary choriocarcinoma were excluded; total β-HCG was 80,000 mU/ml. The patient received cisplatin plus etoposide with moderate clinical improvement and rapid decrease of β-HCG level. Invasive carcinoma