Pleomorphic adenoma (benign mixed tumor) of the salivary glands is a benign, slowly growing neoplasm that has a predilection to the parotid where 80% of these tumors arise. It is often firm, nodular, painless and almost always unilateral. Women are more affected than men. Facial nerve function is usually not affected, even in very large tumors. About 2/3 arise in the superficial lobe of the parotid, but occasionally, they extend medially into the pharynx. Malignant degeneration could occur in 3 - 5 % of the cases.
Axial CT scan of the neck showing a left parotid gland pleomorphic adenoma.
Right parotid pleomorphic adenoma on axial MRI scan of the neck. Note the heterogenous appearance.
Right parotid pleomorphic adenoma on coronal MRI scan of the neck.
These masses are typically solitary, non-infiltrating and well demarcated. They may appear heterogeneous secondary to hemorrhage, calcification, and necrosis.