Background  Mucoepidermoid carcinoma (MEC), which is a common malignant salivary gland neoplasm, is rarely seen in the lacrimal gland. More comprehensive information is therefore needed to be summarized to guide the diagnosis and treatment of the disease.

  Objective  To explore the clinical features, image characteristics, diagnosis, treatment, and prognosis of lacrimal MEC.

  Methods  The clinical image and pathological data of 24 patients with lacrimal gland MEC confirmed in the Third Medical Center of Chinese PLA General Hospital from January 2010 to December 2021 were retrospectively analyzed.

  Results  The average age of the 24 patients was 56.35 years, and the male to female ratio was 7:1. Of the 24 cases, there were 21 cases (87.5%) of proptosis, 16 cases (66.7%) of supraorbital palpable mass, and 3 cases (12.5%) of periorbital pain. There were 19 cases of primary lacrimal gland MEC, 5 cases of postoperative malignant changing to MEC, and 6 cases of distant metastasis. Among the CT images of 10 cases of lacrimal MEC, 7 cases manifested as inhomogeneous with soft-tissue density, 9 were irregularly shaped, 7 showed signs of calcifications in tumors, and 7 showed bone destruction around. Of the 8 cases undergoing MRI, all showed soft-tissue mass with marked inhomogeneous enhancement and liquefaction necrosis, 4 cases were irregularly shaped, and 3 had intracranial, sinus, and temporal fossa invasion. All of these patients were treated with surgical excision. Pathology confirmed that all cases were high-grade MEC, of which 20 (83.3%) showed tumor invasion of nerves, tumor cell necrosis, and more than 4 mitoses/10 HPF. There were 9 cases (37.5%) with bony invasion. One of the 7 patients who were followed-up had recurrence (follow-up time was 12 months), the others did not (mean follow-up was 24.3 months).

  Conclusion  High-grade MEC of the lacrimal gland is likely to occur in middle-aged and elderly men, often manifested as painless proptosis. The majority of images appear as extraorbital middle density occupying lesions with irregular shape, calcification and bone destruction, and a visible liquefied cavity that can invade adjacent tissue structure. Surgical resection is the main treatment, but postoperative recurrence and distant metastasis should be aware of.