What happened, in summary

A 66-year-old woman was referred for six months of right-sided nasal blockage and occasional clear discharge. She had previously undergone neoadjuvant chemotherapy and bilateral mastectomy for breast cancer 10 years earlier. Pathology had shown invasive ductal carcinoma in the left breast and invasive lobular carcinoma in the right. She then completed five years of tamoxifen.

Two years after the breast surgery, cancer spread to the liver and bone. She began palliative capecitabine and bisphosphonates, and the metastatic disease remained stable under oncology review. The later nasal symptoms led to CT imaging, which showed a polyp arising from the skull base. An endoscopic right nasal polypectomy was performed.

Pathology revealed two cancers within the same specimen. Most of the polyp was an olfactory neuroblastoma, but small nests of cells inside it represented metastatic lobular breast carcinoma. Those cells were strongly estrogen- and progesterone-receptor positive, HER2-negative, and E-cadherin negative. Review of older imaging suggested that the olfactory neuroblastoma may have been present with little growth for about a decade.

After surgery, the nasal obstruction and reduced sense of smell resolved, and CT and MRI showed no residual local disease. A multidisciplinary team restarted capecitabine, and she continued regular follow-up for metastatic breast cancer.