Salivary gland tumors: Pearls

• The smaller the salivary gland, the higher the rate of malignancy
• Most of the lesions in the parotid gland are likely to be benign (less than 30% of focal parotid lesions are malignant), 50% of focal submandibular gland lesions are malignant, and more than 70% of sublingual gland lesions are malignant.
• 80% of parotid benign lesions are pleomorphic adenomas
• Multiple parotid masses are usually lymphadenopathy or Warthin tumors
• Warthin tumor occurs almost exclusively in parotid gland, usually in tail in older men
• Most common malignancy of parotid gland is mucoepidermoid carcinoma
• Most common benign lesion of SMG is pleomorphic adenoma
• Most common malignancy in SMG is adenoid cystic carcinoma
• MR imaging in parotid gland tumors:
  Virtually all parotid lesions are well seen on T1 because of hyperintense fatty background of the gland. T1 also shows margin, extent and infiltration
  Fat sat post Gd T1 shows perineural spread, bone invasion, meningeal infiltration, bone marrow changes
• Hyperintense mass on T2-weighted images is usually benign and a mass of low to intermediate signal intensity is usually malignant

References:
1. Yousem DM et al. Major salivary gland imaging. Radiology. 2000;216:19-29