Epithelial–myoepithelial carcinoma of the parotid gland with primary lung cancer: A rare case report

INTRODUCTION: Epithelial–myoepithelial carcinoma (EMC) is a rare, low-grade malignancy that occurs primarily in the parotid gland and is most common in women aged 60 to 70 years. Cases of parotid EMC have been reported previously. Furthermore, some studies have suggested an increased risk of salivary gland tumors with secondary primary malignancies. There have been few reports of parotid EMC with other primary tumors. PATIENT CONCERNS: A 62-year-old Chinese man visited the hospital with a complaint of a mass on his left cheek that had persisted for 20 years. Routine pulmonary computed tomography showed a local ground glass shadow in the lower lobe of the right lung. DIAGNOSIS: The pathological diagnosis of lung was right lower lobe lung adenocarcinoma (pT1N0). Immunohistochemistry analysis showed that cytokeratin (CK)-7, NapsinA, and thyroid transcription factor-1 tested positive, while CK5/6, P40, and ALKD5F3 tested negative. The pathological diagnosis of left parotid gland: EMC. On immunohistochemistry staining, the outer cells expressed myoepithelial markers, such as CK5/6, P63, smooth muscle actin, while the inner cells expressed glandular epithelial markers, such as low-molecular-weight CK7 and CK8. INTERVENTIONS: The patient underwent resection of the lung and parotid tumors, and received preventive radiotherapy in the parotid gland area. OUTCOMES: The patient is in good condition. No symptom recurrence, distant metastatic spread or significant toxicity occurred during or after the treatment. The patient remains under regular surveillance. CONCLUSION: We report a rare case of parotid EMC with a second primary lung adenocarcinoma. This case is the third case of primary lung cancer associated with parotid EMC reported to date and the first to be reported in nearly 30 years.