Salivary Gland Tumours Flashcards
What are the causes of changes in salivary gland size?
Secretion retention
-> Mucocele
-> Duct obstruction
Chronic sialadenitis- associated with mumps, bacterial infections, other pathology
Gland hyperplasia
-> Sialosis
-> Sjögren’s Syndrome
Salivary neoplasms
What are the features of sialosis?
Gland enlargement not caused by infection, inflammation or neoplasm
- Non-tender
- Often occurs in parotid- marked change in size and shape
- Associated with alcoholism, cirrhosis eating disorders, diabetes
How do major salivary gland tumours tend to present?
Localised swelling
Neurological change- swelling in parotid presses on facial nerve
-> Palsy, paraesthesia
What are the usual features of salivary gland tumours?
Painless
Slow growing
Well defined
Benign- 75%
-> malignant tumours are on increase
What is the prevalence of salivary gland tumours?
10 in every 100,000
Which factors may be involved in aetiology of salivary gland tumours?
Radiation
-> occupational
-> mobile phones
Viruses- EBV
Racial susceptibility
Distribution of Salivary Gland tumours:
Parotid- 80% of all tumours/15% malignant
Submandibular- 10% of all tumours/30% malignant
Sublingual- 0.5% of all tumours/80% malignant
Minor glands- 10% of all tumours/45% malignant
-> Smaller the major gland the smaller the incidence tumours- But more are malignant
What are the types of salivary gland tumours?
Epithelial Neoplasms
-> Benign (adenoma)- 11 types *
-> malignant (adenocarcinoma)- 20 types *
Non-epithelial
-> Saroma- fibrous tissue
-> Lymphoma
- subgroups also present
What are the clinical signs of major gland tumours?
Lump in gland
Asymmetry
Obstruction
Later
-> Pain
-> Facial palsy
What are the clinical signs of minor gland tumours?
Occurring in Junction of hard/soft palate, upper or cheek
-> Ulcerate late (suggestive of malignancy)
What techniques are used to investigate and diagnose salivary gland tumours
Fine needle aspirate
Core biopsy (done under LA- gets more tissue than FNA)
Incisional biopsy
What are the features/functions of a FNA?
- Can be done for any swelling underneath the skin
- Used for breast and salivary gland pathology
- Only gives small amount of tissue- can tell surgeon whether benign or malignant but may not help with definitive diagnosis
- Non-invasive
What are the issues when diagnosis salivary gland tumours?
Number of tumour types
Variation within a tumour because tissues originate from different stem cell lines so pathology may be complex
Common features between types
Not all tumours fit the classification
Immunohistochemistry may be needed to differentiate many of these tumours.
-> Molecular markers/next generation sequencing used in some cases (key genomic alterations)
What is meant by the term Adenocarcinoma NOS and when is it used?
Not otherwise specified
- If tumour cannot be placed into a category
What is meant by pleomorphic?
There are a variety of tissue appearances within the tumour
-> no 2 will be the same
What are the histological features of a pleomorphic adenoma?
- Presence of myoepithelial cells- look like muscles cells and can contract (can move saliva through duct)
- Myxoid areas - loose and gelatinous (challenging removal- easy to leave bits behind, can give rise to other tumours)
- Chondroid areas- looks like cartilage tissue formation
- Fibrous Capsule- may be incomplete (allows tumour to grow out into other tissue)
Where do pleomorphic adenomas tend to occur?
Parotid
What % of all salivary gland tumours do pleomorphic adenomas make up?
75%
How are pleomorphic adenomas managed?
Wide local excision
-> Healthy tissue around the PA is removed to help recurrence
Follow up for 5 years due to recurrence risk (larger risk with minor glands)
Why do pleomorphic adenomas have a high recurrence rate?
Multifocal- recurrence can be 2 or 3 from one original tumour
- During removal due to myxomatous tissue parts can easily fall off and continue growing
What is the risk of a Pleomorphic adenoma going undetected or untreated over the course of many years?
Malignant transformation into a Carcinoma ex-pleomorphic adenoma
-> 5%
What are the presenting features of Warthin’s tumour?
- Occasional multiple/bilateral
- Mostly occurs in parotid
- Multifocal
- Occurring more in woman
What are the histological characteristics of Warthin’s tumour?
Completely encapsulated (easy to remove, recurrence is rare, malignant transformation is rare)
Cystic spaces between epithelium with lymphoid tissue in between
Oncocytic epithelium- appears pink
How are warthins tumours treated?
Excision
What % of salivary gland tumours overall are malignant?
15%
What is the incidence of Adenoid cystic carcinoma?
5% (more in minor glands)
Where do adenoid cystic carcinomas typically spread to?
Local
-> Nerves
-> Bones
Late- spreads by blood to lung
What are the issues with Adenoid Cystic Carcinomas?
Difficult to treat
High levels of recurrence
Poor prognosis- very infiltrative and difficult to complete irradicate (grows between trabeculae and along nerve fibres, can spread into myelin sheath)
Can cause disruption of nearby vital structures- nasal cavity, pharynx, maxillary sinus
What are the histological patterns seen in adenoid cystic carcinomas?
Swiss cheese appearance (cribriform)- filled with ground substance (this type has better prognosis)
Tubular
Solid
How does ACC progress?
Slow growing, painless nodule that becomes painful and ulcerated
What are the 2 cell types in mucoepidermoid carcinoma?
Squamous- epidermoid
Glandular- mucous
What are the types of mucoepidermoid carcinoma?
Cystic
Solid
What are the features of mucoepidermoid carcinomas?
- Unpredictable behaviour- variable speed of growth
- Source within jaw bone- mucous cells
- Lymphatic spread can occur
- Bleeding can be present histologically
What stain can be helpful for looking at MEC?
Alcian blue- special stain for mucous cells
What is the scoring system in MEC?
Intra cystic component <20% = 2
Presence of neural invasion = 2
Presence of necrosis = 3
Mitoses = 3
Presence of anaplasia = 4
What grade is given to each score in MEC?
Low grade malignancy- 0 to 4
Intermediate- 5 to 6
High grade- 7 to 14
What are the features of acinic cell carcinoma?
Slow growing
Less aggressive
Varied histology and behaviour
Mostly occurs in parotid
What are the features of polymorphous adenocarcinoma?
Occurs in minor glands in palate
Locally infiltrative (nerves)
