Mucoepidermoid carcinoma. Light micrograph (LM) of a section through a mucoepidermoid carcinoma. Mucoepidermoid carcinomas are the most common type of salivary gland cancer. Most start in the parotid glands. They develop less often in the submandibular glands or in minor salivary glands inside the mouth. These cancers are usually low grade, but they can also be intermediate or high grade. Tumours are composed of mucinous cells admixed with epidermoid cells. Magnification: x50 when printed at 10 centimetres wide.