Salivary gland tumors are variable in location, origin, and malignant potential.
Pathology
In general, the ratio of benign to malignant tumors is proportional to the gland size; i.e. the parotid gland tends to have benign neoplasms, the submandibular gland 50:50, and the sublingual glands and accessory glands mostly malignant. Due to the size discrepancy, in absolute numbers, the parotid gland has the most tumors.
Location
- parotid gland: 70%
- minor salivary glands (including sublingual): 22% with the palate being most frequent (see: minor salivary gland tumors)
- submandibular gland: 8%
Overall ~80% of all parotid masses are benign and the majority of these are pleomorphic adenomas.
Subtypes
Benign
-
epithelial
- pleomorphic adenoma: this is the most common (≈50%) tumor of the parotid
- Warthin tumor: essentially only found in the parotid, in older, usually male patients; it is bilateral in 10-15%
- intraductal papilloma of salivary glands
- oncocytoma of salivary glands
- myoepithelioma: until recently considered a subtype of pleomorphic adenoma; they can also originate in breast and bronchus
- non-epithelial
Malignant
- mucoepidermoid carcinoma: most of the malignant lesions
- adenoid cystic carcinoma
- myoepithelioma
- adenocarcinoma (not otherwise specified)
- acinic cell carcinoma of salivary glands
- squamous cell carcinoma of salivary glands
- lymphoepithelial carcinoma
-
malignant mixed tumors of the salivary glands
- carcinoma ex pleomorphic adenoma
- carcinosarcoma (true mixed tumor of the salivary glands)
- metastasizing pleomorphic adenoma
- salivary duct carcinoma 7
- metastases (mostly to intraparotid lymph nodes) 5
- cutaneous squamous cell carcinoma
- malignant melanoma
- testicular seminoma (rare) 8
- lymphoma (rare)
- primary: arising from the parotid gland as a MALToma 6
- secondary: involving the intraparotid lymph nodes 6
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