Salivary gland disease Flashcards
What are the major and minor salivary glands?
Major includes parotid, submandibular and sublingual.
Minor glands are throughout the mouth.
What are the parotid glands, their location and structure?
They are large, bilateral and in the preauricular region, overlying and fitting behind the ramus of the mandible. There is a superficial lobe which is flat and separated from the deep lobe (pyramid) and it can have accessory lobes. The facial nerve (cranial nerve VII) passes through it. The parotid gland is driven by parasympathetic secretomotor drive from otic ganglion. It delivers through stensons duct which runs along the cheek, perforating buccinator and emerging in the buccal mucosa approximately next to the first upper molar. It produces mainly serous secretion and contributes 20-40% of total saliva. It accounts for 60%of total salivary gland tissue.
What are the submandibular glands, their location and structure?
They are smaller and they are paired glands which are walnut sized. They are found in the upper neck, curving around the posterior edge of the mylohyoid muscle. They have long ducts called Wartons duct which emerges either side of the base of the lingual frenum (punctum). They are palpable if dilated or if containing a stone. The lingual nerve twists around the submandibular duct and the hypoglossus so the lingual nerve needs to be protected. The facial artery runs through it from behind digastric, emerging at the lower border of the mandible at the site of VIIm branch. It has a secretomotor supply from the submandibular ganglion which is suspended off the elbow of the lingual nerve. They produce mixed saliva (mucous and serous). It contributes 60-70% of total saliva. It accounts for 30% of total salivary gland tissue.
What are the sublingual glands, their location and structure?
The sublingual glands are the smallest and they are bilateral glands located in the floor of the mouth under the tongue, suspended from the submandibular duct. They secrete into the ducts of rivinus (10 small ducts) some of which drain into the submandibular duct. It has secretomotor supply via chorda tympani (VII nerve, submandibular ganglion). It has mixed secretion but mainly mucous and contributes 10%. Removal of the sublingual ducts is rarely indicated except in ranula which is a risk to the lingual nerve. They account for 5% of total salivary gland tissue.
What are the minor salivary glands?
Minor salivary glands are found throughout the mouth mainly in the lips, cheeks, palate and tongue. There are approximately 800+ in total. There is parasympathetic supply from the otic ganglion and they have mucous secretion (one exception – posterior lateral tongue). They contribute 5-10% of saliva. They are commonly seen in the lip vermillion. They can become traumatised and blocked. They account for 5% of total salivary gland tissue.
What is the organisational structure of salivary glands and their function?
You produce between 1-2L of saliva per 24 hours. The organisational structure includes acini which are saliva producing cells and demilunes. The initial fluid is secreted into the ductal system and there are intercalated/striated and secretory ducts. Protein and ion content is modified within the duct and there is ion exchange in striated ducts. Increasing diameter ductules drain into the main duct. Myoepithelial cells squeeze product at peak demand. Saliva components include proteins, calcium, phosphate, mucins, immunoglobulins and enzymes. The function of saliva is remineralisation, inhibition of demineralisation, anti-bacterial/fungal/viral, bolus, taste, digestion, buffering and lubrication. All components are critical for full oral health. Drugs, disease and radiation can affect.
How should you examine the salivary glands?
- Feel outline, texture, size relative to opposite side, feel for a lump
- Bidigital exam of glands
- Look for and identify punctum/orifice
- Dry with gauze
- Swipe with pressure along malar or press up in neck – any product/quality/pus/blood
- Microswab/salivary protein/flow rate
- Ask about pain, dry mouth, mealtime syndrome (common, due to stone, stricture or debris sludge), mass effects, cranial nerve neuropathy (VII), ask about intermittent vs increasing
What should you use to diagnose salivary gland disease?
- Clinical history, thorough general and specific examination
- Suitable imaging – USS/MRI/possible CT
- Sialography only indicative
- Histology – direct biopsy, FNA, core needle biopsy – gold standard, don’t do FNA
- Immuno may add to plain histological diagnosis
- Unusual or secondary tumours may need further histological examination/specialist referral
What are the non-neoplastic lesions of salivary glands?
- Developmental anomalies
- Inflammatory - sialoadenitis
- Obstruction and trauma
What are developmental anomalies?
They are very rare. You may see aplasia which is usually associated with other anomalies or syndromes. There is occasionally heterotopic salivary tissue where it is present somewhere it shouldn’t be. Stafne’s bone cavity presents close to the angle of the mandible and appears as a round radiolucency.
What are the types of sialoadenitis and the causes?
Acute: - Bacterial - Viral Chronic: - Bacterial - Post-irradiation - Autoimmune e.g. Sjogren's syndrome - General debility/dehydration/terminal illness/diabetes mellitus/alcohol
What is bacterial sialoadenitis?
Bacterial sialoadenitits predominantly involves the parotid gland and is termed acute (ascending) parotitis. It is an ascending infection caused by oral bacteria (s.aureus). You get acute swelling, heat and pain. Pus exudes from ducts. It is usually secondary to a dry mouth which may be due to radiotherapy, Sjogren’s syndrome or drug-induced.
What are the two forms of recurrent parotitis?
- In adults - recurrent infection secondary to dry mouth
- In children - recurrent parotitis of childhood
- Both forms appear to be associated with ascending infection, often staph aureus
What is recurrent parotitis in adults?
It occurs at 40-60 years and more in females. It is often unilateral. It is secondary to xerostomia. It is due to recurrent ascending infections. It is often secondary to Sjogren’s syndrome, drug induced dry mouth and radiation damage.
What is recurrent parotitis of childhood?
It occurs at ages 4 months-15 years. Males and females are equal. It may resolve at puberty. There are bilateral parotid swellings with a sudden onset. It has days-week duration with periods of quiescence. Its not suppurative. There is no obvious cause or predisposing factors. There may be evidence of infection such as pain, redness and fever. Sialography will show punctate sialectasis radiographically which appears like leaves on a tree. There is gradual destruction of acinar elements and reduced flow. Histologically acini cells are damages and this is irreversible. There will be lots of inflammation.
What is the prevalence and incubation period of viral sialoadenitis?
It is mumps (epidemic parotitis). It is caused by the mumps virus (paramyxovirus). It is now quite rare and there are less than 1000 cases per year. There was a 2006-08 epidemic. The incubation period is 2-3 weeks and it has direct or droplet spread. The numbers were quite high until 1988 until MMR vaccine was introduced and since then numbers have decreased.
What is mumps?
It is acute bilateral parotid swelling which can be unilateral. It is usually in children. It is very painful and there is malaise and fever. It is self-limiting in 10-14 days. It may spread to other glands/organs.
What are the complications of mumps?
- Orchitis in 30%
- Meningitis in 10%
- Oopohoritis 5%
- Pancreatitis 5%
- Cranial nerve palsies
VIII nerve deafness
What is chronic sialoadenitis and where does it usually occur?
Chronic sialoadenitis is the most commonly seen and it is usually secondary to duct obstruction due to calculi. Salivary calculi is an accumulation of calcium and phosphate salts which deposit in the salivary ducts or gland. Histologically calculus is seen as a concentric accumulation of calcium salts around cellular debris and mucous. It is usually unilateral. The male to female ratio is 2:1. It is 80% seen in the submandibular gland, 20% in the parotid and 1-15% in the minor salivary glands. 35% is seen in the floor of mouth, 35% in the posterior duct and 30% in the gland itself so it is evenly distributed.
How can a duct become blocked?
There can be narrowing of the duct or thickening of saliva. This leads to obstruction by calculus leading to saliva retention and inflammation. This leads to swelling and fibrosis and therefore loss of function. Fibrous tissue narrows the ducts. This is most common in submandibular gland as it has mucous saliva which is thicker and the duct is not straight so obstruction is more common. The submandibular gland is also pushing the saliva against gravity. There will be less acini and lots of lymphocytes. The swollen painful gland can occur at mealtimes or when thinking/smelling food.
What colour are serous and mucous acini histologically?
Serous acini are darker purple and mucous acini are lighter.
What is radiation sialoadenitis?
It occurs at doses over about 20Gy. There is a high risk of permanent damage over 30Gy and severe damage over 50Gy. Serous acini are most sensitive. There is inflammation and fibrosis of glands. There is loss of function. It is an important consideration in cancer patients. Histologically you still see ducts but hardly any acini and lots of inflammatory cells.
What is the most common cause of sialoadenitis and what can this result in?
The most common cause is obstruction and trauma. As a result you can get salivary calculi (stones), mucous cysts (mucoceles) and necrotising sialometaplasia.
What is sialolithiasis and the treatment options?
Sialolithiasis is the formation of stones within ducts of the major salivary glands. There are many myths relating to aetiology such as dehydration. There is a likely nidus around which calcium salts are deposited. It is affected by confirmation of the duct and flow rate. There is the ball valve effect with obstruction and temporary flow restriction. There will be expansion and pain from the gland capsule and the stone may travel, exfoliate at the duct orifice or become larger. Sialolithotripsy/basket retrieval/laser fragmentation/local release are more conservative treatment options compared to whole gland excision.
What is sialosis and the treatment?
Sialosis is bilateral, painless swelling of the parotid glands. There is reduced function and the patient will get xerostomia. It can be due to diabetes, drugs or alcohol. There should be supportive treatment or excision.
What are mucoceles and the types?
They are painless swellings which rupture and recur. The lower lip is the most common site and it is most common in children. The types are mucous extravasation cyst and mucous retention cyst. The most common is mucous extravasation cyst. Mucoceles can also raise on the palate, tongue and cheeks but it is not very common. Excise under LA with the minor salivary gland. There will be a scar so care with the vermillion border.
What are mucous extravasation cysts?
They are 85% of mucoceles and occur in a younger age group the peak of which is 20-30 years. The lower lip is the most common site (in 50%+). You get them as there is a break in the salivary duct so saliva leaks and pools in the connective tissue. It has a wall of fibrous and granulation tissue and not an epithelial lining. Histologically the lumen is lined with mucous, there are macrophages filled with mucous, lining of inflamed compressed granulation tissue.
What are mucous retention cysts?
They are 15% of mucoceles so not as common. They are seen in older age groups often over 40 years. The peak age is 50-60 years. They are seen in the floor of mouth and buccal mucosa so a different site. The retention cyst is caused due to a blocked duct so saliva cannot get out, there is backpressure and the duct swells and enlarges. It is lined by duct epithelium. Histologically the lumen is lined with mucous and it has a lining of ductal epithelium. The cyst wall is fibrous tissue with glands and not as much epithelium.
What is a ranula?
They arise in the floor of the mouth and are usually extravasation cysts. They arise from the sublingual gland and are painless swellings. They rupture and recur and are usually 2-3cm. They are usually seen in children. The management is surgical excision and possible exploration of the neck, excision with sublingual gland or decompression and ligation (new) where you take the roof off and ligate the base.
What is necrotising sialometaplasia?
It is important as it can be mistaken for malignancy. It presents as an indurated, ulcerated swelling. It is usually seen on the palate and often biopsied as malignant. It heals spontaneously in 4-8 weeks. It is benign inflammatory disease. Histologically it may look like a carcinoma due to proliferation of stratified squamous epithelium. You get squamous metaplasia of salivary ducts and islands of squamous epithelium deep in connective tissues. But you also see necrosis of acini with ghosts of normal structures.
What are the most common salivary epithelial tumours?
They are classified by WHO 2017 and there are 35+ tumours. The most common ones: Benign: - Pleomorphic adenoma - Warthin tumour - Cystadenoma - Basal cell adenoma - Canalicular adenoma Malignant: - Mucoepidermoid carcinoma - Acinic cell carcinoma - Polymorphous adenocarcinoma - Adenoid cystic carcinoma - Carcinoma ex pleomorphic adenoma
What is the difference between adenomas and carcinomas?
Epithelial tumours are divided into adenomas or carcinomas. Adenomas develop from glandular tissue and carcinoma develops in tissues that line the inner or outer surfaces of the body. Adenomas are benign and carcinomas are malignant. Adenomas can affect people of any age and carcinomas rarely affect children.
What are the non-epithelial tumours?
- Soft tissue tumours
- Malignant lymphomas
- Secondary tumours
- Unclassified tumours
- Tumour like lesions
What is the epidemiology of salivary gland tumours?
There are approximately 1000 malignant salivary gland tumours per year in the UK. 70% of tumours are parotid, 9% submandibular and 1% sublingual so 80% are seen in the major salivary glands. 70% are pleomorphic adenomas and 90% are benign. Only 20% are in the minor glands. Minor gland tumours are more commonly malignant (50%). Sublingual tumours are 99% malignant. There is a wide age distribution of salivary gland tumours and mostly in older patients. 80% of tumours in major glands are benign.
What is the site distribution in minor glands?
- Palate 55%
- Lips 15% (95% of these in upper lip and almost always benign, more likely to be malignant in lower lip)
- Cheek 10%
- Tongue 10%
- Other 10%
What is a pleomorphic adenoma and the epidemiology?
It is the most common salivary gland tumour. The parotid is the most common site and the palate is the next common. It is 70% of major gland tumours and 45% of minor gland tumours. The age range is 30-60 and male and female are equal. It is benign, grows steadily and can become very large and entangled in the facial nerve. If fit and well excise the adenoma as it can have malignant change. A wide excision is critical the first time as any residual capsule may contain elements of tumour. It may recur, recurrence may be late, extensive or ‘scattergun’. It is difficult to treat if multiple recurrences occur, especially outside the gland.
What is the histopathology of a pleomorphic adenoma?
- It has a mixed pleomorphic pattern with a variety of appearances and patterns
- Islands and strands of epithelial cells
- Ductal structures are common
- Myxoid, mucoid or chondroid stroma
- It is encapsulated and lobules are within a capsule
- Often lobular pattern
- Infiltration of tumour into capsule may be seen
- Stroma surrounding tumour is abnormal - bluish appearance (myxoid), can see cartilage sometimes (chondroid) and this is the only tumour that shows this
What is a Warthins tumour, the epidemiology and histology?
It is 10% of benign salivary gland tumours and is always in the parotid gland. It is completely benign and is sometimes bilateral or multifocal. It is more common in males (60:40), smokers and occurs later (60 years). Histologically you see irregular cysts, lined by oncocytic duct epithelium (pink and two nuclei), the stroma is composed of lymphoid tissue which is dense.
What is a mucoepidermoid carcinoma, the epidemiology and histology?
It is the most common malignant salivary gland tumour and is 20% of minor and 5% of major gland lesions. The parotid is the most common site, then the palate, cheek and retromolar pad (if a patient thinks they have a mucocele on retromolar pad its not possible so its this). It is seen occasionally in children. It is malignant and about 10-15% metastasise. Histologically there is a mixture of mucous cells (pale blue cells) and epidermoid (squamous cells). Lesions are usually multicystic and high grade lesions may be solid with few mucus cells and occasional lesions have many clear cells.
What is an adenoid cystic carcinoma, the epidemiology and histology?
It is the second most common malignant tumour and is 15% of minor and 5% of major gland lesions. The parotid is the most common site and then the palate, cheek and sinuses. It is highly malignant. 75% of patients die within 20 years. Metastasis is via the bloodstream and nerve invasion. Histologically it is an infiltrative tumour with no capsule and has a characteristic multicystic or cribriform pattern (swiss cheese). It infiltrates widely through bone, blood vessels and along nerves.
What is a polymorphous adenocarcinoma, the epidemiology and histology?
It used to be called polymorphous low grade adenocarcinoma but the name was changed in 2017. It is similar to mucoepidermoid and it is only found intraorally. It is usually seen in the palate (70%) and in the lips and cheek (30%). It is the third most common intraoral malignancy. It is usually seen in over 50 years. There is infiltrative growth. This and adenoid cystic carcinoma are the most common salivary cancers that infiltrate nerves. It is often misdiagnosed on incisional biopsies as pleomorphic adenoma or adenoid cystic carcinoma. You need great care with small palatal biopsies. The overall survival is over 90% at 5 years and it metastasises in 10-15% of cases. It shows a variable histological pattern including lobules (well demarcated lobular outline), ductal structures, cribriform areas, papillary cystic pattern, single cell filing and washout out nuclei (staining very pale). Perineural infiltration is typical (eye of the storm appearance histologically). There is bland, monotonous cytology. It can be unpredictable and lesions with a papillary cystic pattern and cytological atypia may have worse prognosis.
What is an acinic cell carcinoma, the epidemiology and histology?
It is about 5% of salivary gland malignancies. It is seen 80% in the parotid and 15% in minor glands. It has a 30% recurrence rate and 15% metastasise. It has a variable histological appearance: solid, microcystic, papillary cystic and follicular. Lymphoid tissue and germinal centres are common.
What is a carcinoma ex pleomorphic adenoma, the epidemiology and histology?
About 10% of pleomorphic adenomas become malignant. It is usually long standing and/or recurrent lesions. It is seen in the elderly (60+). There will be a history of a long term slow growing lesion with a recent increase in size. Histologically it may appear to be a typical pleomorphic adenoma but it will show areas of cytological atypia. Some lesions contain other types of carcinoma - adenoid cystic, adenocarcinoma etc.
What is a parotidectomy and extralesional dissection?
Parotidectomy can be conservative, radical or extended. Associated with neck dissection. Extralesional dissection aims to minimise surgical defect and VII nerve risk. Careful nerve function monitoring, no attempt to dissect trunk of nerve. Just removes lump.
What are tumour like lesions?
- Oncocytosis
- Necrotising sialometaplasia
- Salivary gland cysts
- Chronic sialoadenitis of submandibular gland
- Lymphoepithelial lesions
What is Sjogren’s syndrome?
It is an autoimmune disorder characterised by lymphocyte mediated destruction of exocrine glands resulting in dry eyes and mouth. Primary SS is dry eyes and mouth and secondary is dry eyes and/or mouth and connective tissue disease (RA/SLE). It occurs 90% in females in middle age. The oral symptoms are dry mouth (dry mucosa and lobulated tongue), infections (candidosis) and caries. There will be dry eyes (keratoconjunctivitis) and parotid swelling in about 20%.
What is the histopathology?
There is lymphocytic infiltrate in salivary glands. In minor glands focal sialoadenitis and in major glands lymphoepithelial lesion. It shows typical lymphoepithelial lesions and the gland is replaced by lymphocytes. Acini disappear but ducts proliferate to form epithelial islands. Epithelial islands are infiltrated by lymphocytes - lymphoepithelial lesion, In about 2-5% of cases these lesions may progress to lymphoma.
What are the causes of xerostomia?
There are a range of causes including diabetes (due to raised blood sugar and polyuria), medication (anti-cholinergics, cytotoxics, sympathomimetics, diuretics, anti-depressants), radiotherapy and autoimmune conditions including SS.
What does the parotid gland contain which the sublingual and submandibular glands do not?
They contain small lymph nodes within them (submandibular and sublingual do not). During embryological development, the parotid gland is encapsulated after the development of the lymphatic system, whereas the submandibular and sublingual glands encapsulate before lymphatic development. Hence, lymph nodes are found normally within the parotid glands but not in submandibular or sublingual glands. Scalp/ear/haematological cancers can spread to/involve intra-parotid lymph nodes. Accordingly there is always a differential diagnosis for parotid gland masses that includes intra-parotid lymph nodes. The history may point you in the right direction.
What imaging can be used for dry mouth, painful swollen gland and a lump in the gland?
For a dry mouth ultrasound is the first line imaging test if you suspect Sjogren’s syndrome and occasionally sialography can be useful.
For a painful and swollen gland plain radiography can be used usually followed by sialography.
For a lump in the gland ultrasound with a core biopsy for tissue diagnosis. For malignant tumours this is followed up with an MRI.
What is the only cause of a dry mouth that can be identified on imaging?
Sjogren’s syndrome. The disease process destroys the gland parenchyma producing a typical pattern of changes on imaging. Appears more speckled.
Why is sublingual gland obstruction rare?
Because it lacks a single duct and there are multiple tiny openings into the floor of the mouth.
Can ultrasounds be used for salivary stones?
They can identify some stones but are not as sensitive as a sialogram.
What imaging would be used for a submandibular obstruction and parotid obstruction?
. For a submandibular obstruction, a lower true 90 degree occlusal and a posterior oblique occlusal film are needed, possibly with a sectional OPT. For a parotid obstruction, an AP extra-oral film plus a small dental film inside the cheek are useful.
What is sialography?
Sialography involves injecting iodinated contrast along the submandibular or parotid ducts. The iodine in the contrast makes it densely radiopaque: stones are less dense than the contrast and they appear as radiolucent filling defects on the image.
What is the treatment for submandibular calculi?
- If visible in the anterior third of the duct then surgical excision usually under local anaesthetic via an intraoral approach
- If small, mobile and anterior to the mylohyoid bend then basket removal is indicated
- If beyond the mylohyoid bend or too big to remove with a basket then excision of the submandibular gland via an extraoral approach
What is basket removal of submandibular calculi?
It is an intraductal technique done under local anaesthetic. A helical wire basket is inserted into the duct opening (closed). Advance past the calculus and open the basket. Calculus is snared within the basket and drawn to the duct opening. It is released from the duct with a small papillotomy incision. No suturing is required (causes stenosis).
What are the complications of basket retrieval?
- Pain and swelling is to be expected post procedure
- Failing to remove the stone
- Getting the basket stuck in the duct (stone adherent to duct wall, needs to be mobile on sialogram)
- Persistent symptoms despite removing the calculus (ductal stenosis post incision?)
What is the treatment for parotid obstruction?
For strictures balloon dilation is used if it is in the extraglandular duct (most common), otherwise superficial parotidectomy.
For stones:
- If visible at the duct opening then simple surgical excision
- If in the extra-glandular duct, anterior to the posterior border of the ramus, small and mobile, then basket retrieval as per submandibular stones
- If in the gland parenchyma or too large to pass down the duct, lithotripsy (shattered with sound waves) or superficial parotidectomy
What is balloon dilation of ductal strictures?
It is an intra-ductal technique which is done under local anaesthesia: typically articaine down the duct mixed with iodinated contrast, this produces topical anaesthesia and enables identification of the stricture site. Also submucosal buccal lidocaine is injected along the course of the duct. There is dilation of the parotid papilla with a lacrimal probe followed by insertion of a 2 or 3mm angioplasty balloon along the duct. The uninflated balloon is positioned across the stricture under X-ray guidance and then inflated to 15psi for 90s. Two or three inflations can be needed.
What are the complications of balloon dilation?
- In some cases the stricture is too tight to pass the balloon even when a fine guide wire is used for navigation
- Despite the local anaesthetic dilation of parotid duct strictures is uncomfortable when the balloon is inflated
- Some strictures will not dilate even after several balloon inflations
- About a third of dilated parotid strictures will re-stenose within 2 years of treatment and will require a repeat procedure
What is the success rate of basket retrieval and balloon dilation?
Baskets overall 68% successful. Balloons overall 76% successful which reduces to 50% after 2 years.
