ear, nose, and throat disorders
Salivary Gland Tumors
Benign tumors with malignant potential
Pleomorphic adenomas (mixed-type tumors) can undergo malignant transformation, but this usually occurs only after the benign tumor has been present for 15 to 20 years. Once malignant degeneration of a pleomorphic adenoma occurs, it is known as carcinoma ex pleomorphic adenoma. Carcinomatous elements in the tumor metastasize, making carcinoma ex pleomorphic adenoma a highly aggressive tumor with very low cure rates regardless of treatment. Benign cylindromas can slowly undergo malignant transformation into adenoid cystic carcinomas, the most common malignant tumor of minor salivary glands (and of the trachea). The peak incidence of this malignant tumor is between ages 40 and 60, and symptoms include severe pain and, often, facial nerve paralysis. It has a propensity for perineural invasion and spread, with disease potentially extending many centimeters from the main tumor mass. Lymphatic spread is not common. Pulmonary metastases are common, although patients can live quite long with them. 