Salivary gland tumors Flashcards
Most common site of salivary tumours
Over 40 different types
Parotid most common (80%) - mostly benign pleomorphic or warthin.
Submandibular (10%) - half of these will be malignant
Sublingual gland - mostly malignant
Minor salivary glands
Imaging features of salivary gland tumours
US: usually hypoechoic relative to parenchyma.
Concerning features = poorly defined margins or heterogenous echogenicity.
MRI: best modality.
PET - cant differentiate benign vs malignant tumours. low grade tumours will have low avidity so not good for assessing these.
How are superficial and deep partoid lobes separated anatomically?
A diagnonal line drawn from the stylomastoid foramen to the retromandibular vein.
Accessory parotid tissue
Where is it usually located?
Anterior to parotid gland overlying the masseter muscle.
Important pathology can also occur within this since its still salivary gland.
What is Boutonniere defect?
How do u know if salivary gland or pathology?
Defect in mylohyoid muscle that allows sublingual gland to herniate through.
Dont mistake for pathology.
It will maintain its normal glandular T1 hyperintensity.
Pleomorphic adenoma
Appearances on MRI?
Are all T2 hyperintense salivary lesions pleomorphic adenomas?
- Well defined and lobulated
- Solitary
- T2 hyperintense
- Internal cyst/haemorrhage
- High ADC
- T2 dark rim
Can turn cancerous in 1% of cases therefore usually resected.
Contrast enhancement which can be heterogenous
Not all T2 hyperintense lesions are pleomorphic adenomas – biopsy needed to confirm
Can transform to malignancy - look for T1 heterogeneity, low T2 and low ADC.
What is significant of stylomandibular tunnel?
This is space between styloid process and mandibular ramus
Widened - if lesion coming from parotid gland
Narrowed - if lesion coming from carotid space or post styloid parapharyngeal space
What is a spilled pleomorphic adenoma?
When during surgery the capsule of tumour is breached and it spilled tumour and seeds.
Patients can present with recurrent tumour years down the line. Hard to excise then.
Approach now is usually to do parotidectomy.
Warthins Tumour
Most common place?
Signal characteristics
Mostly parotid tail but can be elsewhere in <10% such as subman glands and cervical nodes
Can be multifocal or bilateral
- Heterogenous
- Cystic components
- Low ADC
- Solid components enhance minimally.
- FDG avid
- Loss of signal on STIR
US:
- ovoid shape. cystic regions
- sponge like anechoic areas
- hypervascular
How to tell if a lesion is arising from submandibular gland vs LN invading in?
Anterior facial vein usually runs along lateral border of SMG
If you seen vein ‘in between’ SMG and lesion then its is probs a LN
Auriculotemporal nerve anatomy
What is a Stafne cyst?
Congenital cyst in manible.
Can mimic tumour.
Parotid space lesions
Differential
Malignant salivary tumours summary
What MRI signs are indicative of malignancy?
Salivary gland tumours
- Low T2 signal
- Ill defined borders on T1
- Central necrosis
- Thin rim enhancement (in benign lesions, rim usually thicker)
Most common malignancy in PAROTID?
Mucoepidermoid cacinoma
Look for low T2 (pleomorphic usually high T2)
Adenoid cystic carcinoma
minor salivary glands (55%)
the second most common in the parotid
- arising from the peripheral parotid ducts
- moderate T2 signal intensity
* strong enhancement - aggressive appearance increases with tumor grade
- perineural spread among HN cancers
T2 is unreliable on this case. Rely on intense homogenous enhancement which is not seen in benign lesions
Non-hodgkins lymphoma
Imaging features?
Low ADC is key.
Infiltrative.
Parotid mets
What are common primary cancers?
These are rare
- Cutaneous SCC
- Melanoma
Tail or superficial lobe
Perineural Spread summary of connections
