Introduction
This topic covers inflammation of the salivary glands (sialoadenitis) and the neoplasms of the major and minor salivary glands. The central points for the exam are the causes of sialoadenitis, the classification of tumors, and the features of pleomorphic adenoma, Warthin tumor, mucoepidermoid carcinoma and adenoid cystic carcinoma.
Sialoadenitis
Sialoadenitis is inflammation of a salivary gland, most often the parotid or submandibular.
Related non-neoplastic lesions: mucocele (extravasation of mucus after duct injury, mainly lower lip, with granulation tissue and macrophages around the mucin) and ranula (a large mucocele of the floor of the mouth).
General features of salivary gland tumors
- They are uncommon. About 80% arise in the parotid, of which about 80% are benign; in the submandibular gland roughly half are malignant; in the minor glands and sublingual gland most are malignant. The smaller the gland, the higher the chance of malignancy.
- Most are epithelial and show a mix of epithelial (duct-type) and myoepithelial differentiation.
- Risk factors: previous radiation, and for Warthin tumor, smoking. Facial nerve palsy in a parotid mass strongly suggests malignancy.