Abstract
RATIONALE: Mucoepidermoid carcinoma (MEC) is one of the most common malignant tumors in salivary glands, with specific histomorphological and molecular characteristics. MEC occurring in breast is more rare. PATIENT CONCERNS: We reported 3 cases of female breast mass, diagnosed as benign nodules by ultrasound. DIAGNOSES: The first 2 cases were pathological diagnosed as breast MEC, low grade, and the third case as breast MEC, medium grade. INTERVENTIONS: After pathological diagnosis, 3 patients have expanded the scope of breast resection and lymph node dissection, with negative margin and no lymph node metastasis. OUTCOMES: In the follow-up observation, the first case was followed up for 24 months, the second case was followed up for 30 months, and the third case was followed up for 12 months. All patients had a good prognosis without evidence of recurrence and metastasis. CONCLUSION: Breast MEC is extremely rare and estrogen receptor, progesterone receptor, and human epidermal growth factor receptor-2 negative breast cancer with a good prognosis, which is different from other highly malignant triple-negative breast cancers. reviewed its clinicopathologic morphological characteristics, immunohistochemical markers and molecular characteristics, prognosis and clinical treatment through literature, in order to understanding its clinicopathology and providing reference for clinical precise treatment.