Breast cancer returning 21 years later as a solitary parotid metastasis

What happened, in summary

A 71-year-old woman presented with several months of gradual swelling in the left parotid gland and a 2 × 2 cm hard lump. Her breast-cancer history stretched back 26 years, when she underwent wide local excision for left invasive ductal carcinoma followed by radiation to the breast, axilla and supraclavicular area.

Five years after that first treatment, the cancer recurred locally with axillary-node involvement. She then underwent completion mastectomy and axillary clearance, followed by 6 cycles of cyclophosphamide, methotrexate and fluorouracil and 8 years of tamoxifen.

Biopsy of the new parotid lesion showed adenocarcinoma with mixed ductal and lobular features consistent with metastatic breast cancer. The metastasis was ER positive and PR positive; HER2 testing was ultimately regarded as negative by FISH. PET-CT showed uptake only in the left parotid lesion, and a bone scan found no other metastatic disease.

Because the parotid lesion represented distant recurrence, her latest breast-cancer stage was Stage IV. She started an aromatase inhibitor. Radiation was considered but not used because the tumour was responding to endocrine treatment. On follow-up, the parotid mass became slightly smaller. More than 5 months after the metastatic diagnosis, her disease remained stable on endocrine therapy.