Epithelial-myoepithelial carcinoma with high-grade transformation of parotid gland: A case report and literature review

RATIONALE: Epithelial-myoepithelial carcinoma (EMC) is regarded as a rare low-grade malignant tumor of the salivary gland, accounting for 0.4% to 1% of all salivary gland tumors. However, epithelial-myoepithelial carcinoma with high-grade transformation (EMC with HGT) is extremely rare, therefore it is easily to be inappropriately diagnosed and treated. Herein, we report an unusual case of EMC with HGT involving the parotid gland and discuss the clinical features and histological characteristic of EMC with HGT, in order to remind the doctors to take appropriate diagnosis and treatment. PATIENT CONCERNS: A 77-year-old female sought for treatment in our hospital due to pain mass in the left parotid gland for 6 months with rapid growth recently. DIAGNOSES: EMC with HGT was confirmed by final pathology, and then the result showed there were 2 distinctly different areas in the tumor, including the typical EMC component and intensive spindle cells component. INTERVENTIONS: The extensive resection surgery was performed. OUTCOMES: The patient was uneventful after surgery and no recurrence or metastasis has been observed after follow-up of 4 years. LESSONS: A review of literature suggested that EMC with HGT patients trend to be more aged, more aggressive and poorer prognosis than typical EMC patients. In order to avoid misdiagnosis and inappropriate treatment, it is necessary to accurately recognize the differences between the EMC with HGT and typical EMC.