Mucoepidermoid carcinoma involves three cell types: squamous cells, mucus-secreting cells, and “intermediate” cells. The main function of mucus-secreting cells is to create mucus. Intermediate cells range from small basal cells, which are small, round cells found in the lower part, or base, of the epidermis, the outer layer of the skin, to larger and more oval cells.
The most common cancer involving mucoepidermoid carcinoma is salivary gland cancer, but it is also found in the Eustachian tube in the ears, larynx (voice box), and the thyroid. Approximately 35 percent of malignancies are mucoepidermoid carcinomas.
Mucoepidermoid carcinoma tumors are classified as low, intermediate, and high grade. High-grade tumors are made primarily of squamous and intermediate cells. Low-grade tumors are made primarily of mucus-secreting and squamous cells. The features of intermediate-grade tumors are somewhere in between low- and high-grade tumors.