A salivary gland neoplasm is an abnormal growth of the cells constituting the salivary glands. These glands are composed of a number of different types of cells, and unregulated growth of these cells causes neoplasms. Some types of neoplasms have malignant characteristics, meaning that they can infiltrate into surrounding structures and can spread to distant regions, whereas others are benign and only have self-limited growth. Neoplasms are often classified according to the cell type that replicated to cause the tumor. Symptoms can include having pain, feeling a lump, or having decreased facial movement or sensation.
In order to understand the different types of salivary gland neoplasms, it helps to know what these glands are and what types of cells constitute them. Humans have large salivary glands located under the tongue, in the regions under the jaw, and in the cheek regions under the ears. There are also smaller glands located in the mouth and in the throat. The function of these glands to produce saliva, a substance important for lubrication of the food and for some preliminary digestion. In order to perform these functions, the salivary glands are made up of glandular cells that produce saliva, cells that line the ducts transporting saliva from the gland into the mouth, muscle cells that help move the saliva into the mouth, and cells that are responsible for generating new cells to replace old ones that no longer function.
Often experts classify a salivary gland neoplasm as being either a benign or malignant tumor. Benign tumors typically only grow in a limited region and do not have the ability to invade surrounding structures or spread to distant regions, whereas malignant tumors do have this ability. One type of benign salivary gland tumor is called a pleomorphic adenoma, and this growth contains a mixture of a number of different types of cells including glandular cells and muscle cells. In contrast, other types of benign salivary gland neoplasms are made of only one cell type. Examples of these tumors include Warthin tumors, basal cell adenomas, and myoepitheliomas.
There are three common types of malignant salivary gland neoplasm. Differentiating between these neoplasms often relies on taking a sample of the tumor, and understanding what salivary gland the neoplasm originated in, as certain types of malignant neoplasms more frequently arise in certain locations. Mucoepidermoid carcinoma is the most common malignant neoplasm, and contains glandular cells and cells that typically line the salivary ducts. The adenoid cystic carcinoma is made of glandular cells, and more commonly arises in smaller salivary glands. Polymorphous low-grade adenocarcinomas also arise from the glandular cells that typically make the saliva.
Symptoms can include having a dry mouth, feeling a lump where a salivary gland is normally located, or having pain in the salivary gland regions. Although some patients have pain, others may have no symptoms other than the development of a mass. Sometimes a salivary gland neoplasm can infiltrate the nerves going to the face, causing paralysis of the facial muscles or facial pain.