When breast cancer gets complicated. A case report of synchronous bilateral breast cancers with discordant tumor markers from the primary to nodes with findings of a sentinel internal mammary subpectoral lymph node.

This case reviews synchronous bilateral breast cancer with left infiltrating ductal carcinoma ER+/PR-, Her2- and right invasive lobular carcinoma ER+/PR-, Her2-. Independent primary bilateral breast tumors are present in 0.2-3.2% of breast cancer. Biopsy also showed differing ER status on the left breast versus the node which was triple negative. The final sentinel node was a left internal mammary node. Recent studies have found that the ER, PR and HER2 status of the primary tumor do not always correlate to the ER, PR and HER2 status of the metastatic sites. This can have deleterious effects on survival. There are no clear guidelines on course of treatment for these complex cases. A review of the current literature is supportive of treating the highest-risk breast malignancy. Despite the unusual pathology and severity of disease, our patient is doing well with treatment.