Dictionary.net

A malignant epithelial tumor of glandular tissue, especially the salivary glands, characterized by acini with mucus-producing cells and by the presence of malignant squamous elements. Most mucoepidermoid tumors are low-grade lesions readily cured by adequate excision. They may appear in any age group. They grow slowly. If high-grade, they behave aggressively, widely infiltrating the salivary gland and producing lymph node and distant metastases. (Dorland, 27th ed; from DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, p575)