Salivary gland disease Flashcards
List the major salivary glands
Parotid
Submandibular
Sublingual
List the basic functions of saliva
- Microorganisms - antifungal, antivital and antibacterial
- Food - mastication, bolus formation, taste and digestion
- teeth - lubrication, remineralisation, buffering, protection against demin
How does saliva protect the oral cavity?
- Lubricates and cleanses the mouth and teeth
- Controls oral PH to allow buffering of bicarbonate
- Limits oral pathogen growth via lysosomes and IgA
- Remineralisation of teeth
What ph level does the saliva maintain in the mouth?
6.2-7.4
What is the rest (unstimulated) flow of saliva
500ml (or up to 1 litre) a day
this is around 0.35ml/min
What is the contribution of rest flow from the salivary glands?
Submandibular 70%
Parotid 20%
Sublingual 5%
Minor 5%
What is the stimulated flow rate? Which gland is responsible?
2ml/min
Parotid gland increases secretion by 5x
What is the dinural flow rate?
Around 0.1ml/min
Lowest flow rate is around 3am
List the differential diagnosis for salivary gland diseases
Infection - bacterial (staph, TB, actinomycosis), viral (mumps, HIV, CMV)
Cysts - mucocoles or ranulas
Tumours - benign or malignant
Systemic conditions - sialadenosis, sarcoidosis, HIV, autoimmune
Obstruction - calculi or strictures
What are some presenting signs of an obstruction?
Intermittent, meal time related swelling or pain
What are presenting signs of sialadenitis
Intermittent non-meal related swelling
List the imaging techniques used for salivary gland disease
Sialography Ultrasound Plain films CT and CT sialography MR sialography Endoscopy
Advantages of ultrasound as an ix for salivary gland disease
- Quick, non-invasive, cheap, good compliance, doesn’t use contrast media or radiation, high resolution
- First line ix
When are plain films indicated?
Ix for calculi as 20-40% of parotid and 60-80% of submandibular stones are radiopaque
Indications for sialography
Contraindications for sialography
Obstruction, sialdenitis, sjogrens
CI - allergy to iodine, acute infection of gland, caulcus at the ostium of the duct
Technique for sialography
Radiopaque medium is introduced into the ducts to demonstrate anatomy
What types of radiopaque materials are used in sialography
Water based (urographic) Oil based - NOT USED AS LESS SAFE
What is the best ix for salivary stones and why?
CT and CT sialography as it is 10x more sensitive for calcification than plain films (100% sensitivity)
Tx options for salivary stones
- Extracorporeal or intracorporeal shockwave lithotripsy
- Stone retrival
- Dissolution
- Conservative surgery
Tx options for strictures
Baloon duct dilation
Indications for basket removal
- Mobile stone
- No stricture distal to the stone
- Stone <50% width of the duct
- Basket can pass the stone
Complications of salivary gland surgery
Nerve damage Facial scarring Post op infection Salivary fistula Frey's syndrome
What is the risk of nerve damage in salivary gland surgery
Parotid - 20-60% temporary, 1-7% risk of permanent damage to the facial nerve
SM gland - marginal mandibular nerve palsy or lingual nerve palsy
Tx options for parotid surgery
- Partial superficial parotidectomy
- Capsular dissection
What is Frey’s syndrome?
Complication of surgery occuring near the parotid gland, characterised by swelling at meal times and flushing of the face
What are the acinar cells?
Clusters of cells acting as the basic secretory unit of the salivary glands. They can be serous or mucous
What are the myoepithelial cells
Cells in the glandular epithelium around the acinar cells, which control luminal functions e.g. flow of fluid
Define: sialosis
Non-pathogenic, non-neoplastic increase in salivary gland size
Define: sialodenitis
Ductal infection
Define sialolithiasis
Duct obstruction
Define sialectasis
Cystic widening of the duct
Define sialorrhea
Excessive salivation or drooling
Aetiology of salivary gland tumours
- Ionising radiaition
- Occupational risks - rubber or car manufacturing, woodworking
- Little is known
- SMOKING AND ALCOHOL PLAY NO ROLE
Pathophysiology of salivary gland tumours
Unknown for most, except in the case of chromosomal translocations
How do chromosomal translocations occur
Non-disjunction at mitosis - there is mutations in the DNA repair genes and random breaks (double-strand break or reciprocal T)
Examples of salivary gland tumours caused by chromosomal translocations
- Pleomorphic adenoma
- Adenoid cystic carcinoma
- Mucoepidermoid carcinoma
- Secretory carcinoma
Presentation of salivary gland tumours
- All ages affected, but risk increases with age
- Lump in gland or mucosal at an intraoral site e.g. palate
- If malignant - there will be signs e.g. pain, ulceration, bone invasion, rapid growth, nerve signs
Where are malignant and benign salivary gland tumours more likely to occur?
Malignant - in minor salivary glands
Benign - in major salivary glands
Which salivary gland tumours are benign?
- Pleomorphic adenoma
- Warthin’s tumour
Which salivary gland tumours are malignant?
- Mucoepidermoid carcinoma
- Polymorphous adenocarcinoma
- Acinic cell carcinoma
- Adenoid cystic carcinoma
List the features of benign salivary gland tumours
- Slow growing
- Well differentiated and encapsulated
- Soft or rubbery consistency
- Do not ulcerate
- No associated nerve signs
- Non-invasive and non-metastatic
- CO aesthetics or pressure
List the features of malignant salivary gland tumours
- Slow or rapid growth
- Non-capsulated
- Can be hard and indurated
- Progressively increase in size
- May be ulcerated
- Can mets
- Signs of malignancy (pain, impaired function, neurological signs)
- imaging shows an irregular pattern of destruction or invasion
What is the most common salivary neoplasm?
Pleomorphic salivary adenoma - around 75% of parotid tumours
List the features of pleomorphic salivary adenomas
- Arise from duct epithelium or myoepithelial cells
- Encapsulated
- Painless and slow growing
Ix for pleomorphic salivary adnoma
- Sialography showing ‘ball-in-hand’
- Histology showing incomplete capsule, ducts, sheets or dark-staining epithelial cells, squamous metaplasia or foci of keratin
How is pleomorphic salivary adenoma diagnosed?
Via FNA
Tx of pleomorphic salivary adenoma
Wide excision
Recurrence risk of pleomorphic salivary adnoma
High risk due to difficulty removing entire tumour due to proximity to facial nerve
Risk is reduced by removing the gland with the tumour
Describe the features of Warthin’s tumour
Almost always in the paortid
Mobile, firm to fluctant
Enlcueated
May be single or multiple
Histology of Warthin’s tumour
Tall, eosinophillic columnar cells forming a folded layer covering lymphoid tissues
Tx to Warthin’s tumour
tends to respond to enucleation
What is the most common malignant salivary neoplasm
Mucoepidermoid carcinoma (3-9% of all salivary gland neoplasm)
Describe the features of mucoepidermoid cecinomas
Most in minor salivary glands (esp palate)
Can be high or low grade
Tx of mucoepidermoid carcinoma
Wide excision with risk of reucrrence
Describe the features of acinic cell carcinoma
Rare (1% of all salivary gland tumours)
Low to intermediate grade salivary neoplasm with serous granules
Often arises in the parotid
Invasive and sometimes mets
Histology for acinic cell carcinoma
Uniform pattern of large cells with granular basophilic cytoplasm
Round holes gives a lace appearance
Describe the features of adenoid cystic carcinoma
Arise in major or minor glands
Initial presentation often nerve palsy or ‘funny feeling’
Slow growth but highly INFILTRATIVE along nerve sheaths
Prognosis for adenoid cystic carcinoma
Very poor 15 year diagnosis due to late presentation (due to slow growth)
Tx for adenoid cystic carcinoma
Wide excision, often combined with radiotherapy at the earliest possible stage
Histological appearance of adenoid cystic carcinoma
Round groups of darkly stained cells with multiple clear spaces (looks like swiss cheese)
What is a carcinoma ex pleomorphic adenoma?
A carcinoma arising from pre-existing pleomorphic adenoma