Imaging of Parotid Tumours and Cancers

Minority of parotid tumours require imaging

Only required if it might change management
Infrequently indicated for clinically benign, mobile parotid tumours as it rarely alters surgical management

Indications

Suspect non-neoplastic disease e.g. HIV lymphoepithelial cyst, TB, benign cyst, lipoma (US / CT)
Deep vs superficial lobe parotid tumour
Mobile tumour: Only if surgeon does not have skill to resect a deep lobe tumour (CT with contrast / MRI)
Reduced mobility/fixed tumour
Deep lobe tumour (CT with contrast / MRI)
Extension to parapharyngeal space (CT with contrast / MRI)
Invasion of local structures (CT / MRI)
Recurrence of benign or malignant tumours (MRI)
Neurological deficits e.g. facial nerve to determine extent of perineural invasion (MRI with Gd)
Metastases to parotid gland (skin, conjunctiva), to plan selective vs therapeutic neck dissection (US / CT / MRI)
Exclude lung metastases with suspected/known malignancy (CXR / CT)

Types of imaging

Ultrasound
- Cystic vs solid; associated cervical lymph nodes
- Not good for deep vs superficial lobe, or for parapharyngeal extension
CT with contrast
- Cystic vs solid; associated cervical lymph nodes
- Deep vs superficial lobe mass, or for parapharyngeal extension (Need to identify retromandibular vein (Need to identify retromandibular vein)
MRI
- Tumour “stuck” around stylomastoid foramen area
- Local invasion (Good soft tissue differentiation)
- Deep vs superficial lobe mass, or for parapharyngeal extension
- Perineural invasion

PET-CT: Unhelpful as benign pathology (pleomorphic adenoma, Warthin tumours, TB, abscesses, lymphoma) are PET-avid