Salivary gland tumours
From Ganfyd
Neoplastic lesions of the salivary glands are divided into benign or malignant. Malignant lesions are further divided into primary and secondary.
Contents |
Classification
Benign
- Pleomorphic adenoma
- Warthin's tumour
- Monomorphic adenoma
- Oncocytoma
Malignant
- Adenoid cystic carcinoma
- Adenocarcinoma
- Squamous cell carcinoma
- Undifferentiated carcinoma
- Carcinoma expleomorphic adenoma
Variable
- Mucoepidermoid carcinoma
- Acinic cell carcinoma
Non epithelial
- Haemangioma
- Lymphangioma
- Neurofibroma
- Lymphoma
About 80% of salivary gland tumours arise in the parotid gland. 80% of these are benign, 80% are pleomorphic adenoma. One in three tumours in the submandibular gland and one in two in the minor salivary glands are malignant.
Clinical assessment
- Inspect the mass
- Inspect the rest of the ears, nose, throat, head and neck
- Check the cranial nerves (if facial nerve palsy, probably malignant tumour)
- Fine needle aspiration is 95% sensitive, and is safe
- Imaging with CT or MRI
Benign tumours
Pleomorphic adenoma
Aetiology
- Commonest benign salivary tumour
- Equal sex distribution
- Peak age of incidence is 50
Pathology
- Most commonly found in the superficial lobe of the parotid
- Has a pseudocapsule formed of compressed parotid
- Arises from several cell types, from intercalated duct cells to myoepithelial cells
- Has characteristic mixed staining pattern
- Unknown if they become malignant. Carcinoma expleomorpha adeonoma may or may not arise from a pleomorphic adenoma.
Surgery
- Aim to preserve the facial nerve using nerve monitoring
- Pseudocapsule rupture can result in seeding of the tumour
- Typically, tumour is removed with a surrounding cuff of normal tissue
- Recurrence is a problem, up to 10% can recurr
Warthin's tumour
Also known as a papillary cystadenoma lymphomatosum or an adenolymphoma.
Aetiology
- Seven times more frequently in men
- Peak age of incidence is 70
- Up to 10% are bilateral
Pathology
- Arise from heterotropic tissue in lymph nodes within the parotid gland
- Cystic appearence
Surgery
Same technique as for pleomorphic ademona
- Much less likely to recurr
Monomorphic adenoma
- Arise from ductal epithelium
- Excised with cuff of tissue
Oncocytoma
- Also known as an Oxyphil adenoma
- Arises from intralobular ducts
- Has potential for malignant change
- Excised with cuff of tissue
Malignant tumours
Malignant tumours of the salivary glands are described using the UICC system.
| Tumour |
|---|
| T0 No evidence of primary tumour |
| T1 Tumour <2 cm, without parenchymal extension |
| T2 Tumour >2 cm but <4 cm, without parenchymal extension |
| T3 Tumour 4-6cm or with parenchymal extension, but without facial nerve invovlement |
| T4 Tumour >6 cm, or invades skull base, or invades facial nerve |
| T4a No local extension |
| T4b Local extension involving skin, soft tissue, bone or nerve |
| Nodes |
| N0 No regional lymph node metastasis |
| N1 Metastasis in single ipsilateral node, <3 cm in greatest diameter |
| N2a Single ispilateral node involvement, 3-6 cm |
| N2b Multiple ipsilateral node involvement, all <6 cm |
| N2c Contrlateral or bilateral node involvement, <6 cm |
| N3 Node involvement >6 cm |
| Metastasis |
| M0 No distant metastasis |
| M1 Distant metastasis |
Adenoid cystic carcinoma
Aetiology
- Commonest malignant salivary tumour
- Equal sex incidence
- Peak age of incidence is 60
Pathology
- More likely to occur in minor salivary glands
- Slow growning and spreads along nerve sheaths
Surgery
- Radical excision of tumour and parotid gland
- Facial nerve may be left behind if unaffected
- Adjuvant radiotherapy
Adenocarcinoma
- 3% of parotid tumours
- 10% of minor salivary gland tumours
Squamous cell carcinoma
- Rare
Variable tumours
Mucoepidermoid carcinoma
- Commonest type of salivary tumour to occur in children (but 97% occur in adults)
- Most ocmmon in parotid gland
- Low grade tumours behave like benign tumours
- High grade tumours metastatise early and carry poor prognosis
Acinic cell carcinoma
- Difficult to classify
- More benign than mucoepidermoid tumours
Complications of parotid surgery
- Haemotoma
- Nerve damage
- Frey's syndrome
- Salivary fistula
Temporary nerve paralysis of the facial nerve occurs in 10% of patients. Permenent dysfunction is rare (less than 2%). Frey's syndrome is gustatory sweating.
Salivary tumours in children
Salivary tumours are rare in children, and occur mainly in the parotid. Only 3% of parotid neoplasms occur in patients under 16 years old.
Benign tumours
Mixed tumours are the most common tumours by far. The peak incidence occurs at 10 years old. The behaviour of the tumours is similar to those in adults. Haemangiomas are the next most common tumour.
Malignant tumours
These are very rare. Well differentiated / high grade mucoepidermoid carcinoma is the most common malignant parotid tumour in children.
