Unusual bilateral parotid metastasis from breast cancer: A case report

Breast cancer is the most common malignancy in women and is known to metastasize to distant organs, including the lungs, liver, bone, and brain. However, metastasis to the parotid glands is an exceedingly rare occurrence, often posing a diagnostic challenge. Parotid metastasis can mimic primary salivary gland tumors, inflammatory conditions, or neurological disorders such as Bell's palsy, leading to delays in diagnosis and treatment. This case report presents an unusual instance of bilateral parotid metastasis from breast cancer and highlights the diagnostic and management challenges associated with this rare phenomenon. A 46-year-old premenopausal woman with a history of invasive ductal carcinoma (IDC) of the right breast, diagnosed in 2018, presented in January 2021 with progressive bilateral parotid swelling, peripheral facial paralysis, and difficulty closing her left eye. She had previously undergone mastectomy, chemotherapy, radiotherapy, and endocrine therapy. Imaging, including ultrasound-guided biopsy and CT scans, confirmed metastatic ductal carcinoma in both parotid glands. Immunohistochemistry results were consistent with the patient's original breast cancer diagnosis, demonstrating estrogen receptor (ER)-positive, progesterone receptor (PR)-positive, and HER2-negative tumors. Despite receiving palliative chemotherapy and radiotherapy, the patient's condition worsened, and she passed away one year after the diagnosis of parotid metastasis. Parotid gland metastasis from breast cancer is a rare but clinically significant manifestation. Due to its rarity, it is often under-recognized, and early diagnosis can be challenging. Advanced imaging techniques such as PET/CT and MRI play a critical role in detecting these rare metastases, though they require careful interpretation. While treatment remains primarily palliative due to the poor prognosis, early recognition and timely palliative care can improve patient quality of life. This case investigates the importance of heightened clinical awareness and advanced imaging in the management of metastatic parotid lesions in breast cancer patients. • Uncommon presentation of bilateral parotid metastasis from invasive ductal carcinoma of the breast. • Initial symptoms mimicked Bell’s palsy, leading to potential diagnostic delay. • Imaging and immunohistochemistry confirmed the metastatic origin from the primary breast tumor. • Emphasizes the importance of considering metastatic disease in patients with atypical parotid and facial nerve presentations. • Early recognition can prevent irreversible facial nerve damage and guide appropriate oncologic management.