Skeletal muscle and brain metastases arising from primary squamous cell carcinoma of the parotid gland: a case report and review of the literature

Salivary gland tumors are less common in comparison to other head and neck tumors. Histological classifications of salivary gland tumor are diverse and complicated. Common malignant salivary gland tumors are mucoepidermoid carcinomas and adenoid cystic carcinomas. Although parotid gland carcinoma is the most common salivary gland tumor, primary squamous cell carcinoma (SCC) of the parotid gland was rarely reported with aggressive biology behavior and high rate of lymph node metastasis. Major metastatic sites of salivary tumors are lung, bone and liver. Skeletal muscle and brain metastases were rarely reported and indicated poor prognosis. Here, we report a case of primary squamous cell carcinoma of the parotid gland with metastases to skeletal muscle and brain after the wide local excision of the left parotid gland followed by adjuvant chemotherapy. According to our knowledge and searched literatures, this is the first report of primary SCC of the parotid gland with skeletal muscle metastases followed by multiple brain metastases.