Ultrastructure of mucoepidermoid carcinoma in minor salivary glands.

Three cases of mucoepidermoid carcinoma of minor salivary glands were studied by electron microscopy. Mucus-secreting cells contained numerous mucous globules and bundles of fine cytoplasmic filaments. Another cell type contained a large number of glycogen particles, akin to tumor cells in glycogen-rich adenocarcinoma, and it is postulated that these cells represent the intermediate cells observed by light microscopy. Epidermoid cells contained a moderate amount of tonofilaments and various numbers of organelles. Mucus-secreting and epidermoid cells that surrounded a cystic space exhibited many microvilli. Results of this study support the theory that mucoepidermoid carcinoma develops from salivary gland duct cells with different cellular differentiation potentials and, in general, agree with the conventional grading system of mucoepidermoid carcinoma.