Abstract: 【Abstract】 Objective To investigate clinical and histopathological features and differential diagnostic considerations of mucoepidermoid carcinoma （MEC）. Methods A retrospective study was carried out on clinical manifestations, histopathological and immunohistochemical features, treatment and prognosis of 8 patients with MEC, who were collected from Department of Pathology, Hospital of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College during 2018 - 2021. Results Among the 8 patients, 5 were males and 3 were females, and their age at onset ranged from 19 to 67 years. Skin lesions were located on the lip mucosa in 5 cases, on the cheek in 2 cases, and on the nose in 1 case. Tumors were all located in the dermis and subcutaneous tissue, parts of which were connected to the epidermis; different proportions of mucous cells, epidermoid cells and intermediate cells were arranged in nests or clumps, and formed solid or cystic structures accompanied by varying degrees of formation of ducts and mucus lakes; all epidermoid cells and intermediate cells expressed cytokeratins AE1/AE3, CK5/6, P63, carcinoembryonic antigen and epithelial membrane antigen. According to the current Chinese grading system, 1 of the 8 patients was diagnosed with intermediate-grade MEC, and others were diagnosed with low-grade MEC. No abnormalities were found by systemic examination. All patients received surgical resections. After the follow-up of 12 - 36 months, no recurrence or distant metastasis was observed. Conclusion MEC presents no characteristic clinical manifestations, its diagnosis mainly depends on histopathological features, and mucus in the cytoplasm of mucous cells as shown by alcian blue staining is specific for MEC.

Key words: Skin neoplasms, Skin manifestation, Pathological process, Mucoepidermoid carcinoma