Metachronous, Single Metastasis to the Parotid, from Primary Breast Cancer: A Case Report and Review of the Literature

Abstract

Background. The parotid gland is an unusual site for metastatic disease and when metastasis occurs, it commonly originates from head and neck primaries. Spread from distant infraclavicular sites such as the breast, into the parotid, is even more unusual with very few cases reported in the literature. Case Report. We describe the case of a 65-year-old woman presenting for a rapidly enlarging right parotid mass. She had a history of an invasive ductal carcinoma of the right breast and was disease-free in the past 6 years prior to her presentation. She was thereafter diagnosed as having a solitary parotid metastasis from breast origin. A total parotidectomy was done and she was referred for adjuvant radiotherapy. Conclusion. Any parotid metastasis should be investigated, especially in patients with a prior history of cancer where the possibility of metastasis, even if improbable, should be kept in mind. Fine needle aspiration biopsy (FNAB) is the first diagnostic procedure to be done and immunocytochemistry can provide valuable information even if it is not always needed for diagnosis. Superficial parotidectomy when feasible with adjuvant radiotherapy is the preferred approach for solitary metastasis of the parotid. The prognosis, however, remains poor regardless of the treatment modality used.

Reminder of an important clinical lesson: breast cancer metastasis to the parotid gland

“…Distinguishing between primary and metastatic salivary gland tumours is important for therapy and prognosis 8. Malignant salivary tumours account for 0.5%–1% of all cancers, and of these only 10% are metastatic 1. Metastatic parotid gland neoplasms account for roughly 9%–14% of all parotid tumours 9…”

“…Some studies theorise that a haematogenous route of metastasis is more feasible 1. This is due to breast cancer metastases to ipsilateral and contralateral parotid tumours being equally reported.…”

“…Presentation has also been reported to be extremely variable; while most patients present with a swelling over the parotid gland, others may have facial nerve palsy as their initial cause for concern. It has been suggested that those who experience nerve palsy are likely to have parotid malignancies 1…”

“…While invasive ductal carcinomas (IDCs) are the most common breast cancer, metachronous metastases from the breast to the parotid gland are extremely rare. Both haematogenous and lymphatic routes of transmission have been reported, thus emphasising our limited knowledge of this disease 1. The importance of this case is evident when considering the rarity of the diagnosis and how easily it can be misdiagnosed.…”

Parotid gland: an unusual site of breast cancer metastasis

“…Making up about 33% of cases, mucoepidermoid carcinoma is the most common type of malignant parotid gland tumour 6. Malignancy of the salivary glands is most commonly due to primary tumours, with metastases only accounting for 10% of tumours 7. While the parotid gland is the most commonly involved salivary gland in secondary cancer, metastases to it from breast cancer are rare.…”