Pathology of salivary gland tumours Flashcards
How can salivary gland neoplasia present in major salivary glands? (3)
- localised swelling = Asymmetry
- Obstruction of the gland
- Neurological change = especially from the facial nerve in parotid
Pressure or infiltration of tumour along the nerve = paraesthesia and facial palsy etc
List the 3 characteristics of salivary gland tumours.
- Painless
- Slow growing
- Well defined
What are the 4 suggested causes of salivary gland tumours?
generally the aetiology is unclear
- mobile phones? (not proven)
- Radiation exposure
- Viruses: EBV = increase in malignant salivary gland tumours
- racial susceptibility ?
What is the general rule regarding salivary gland size and % malignancy?
The larger the gland the lower the incidence of malignancy/malignant tumours will be
parotid = 80% of tumour occur here and 15% are malignant
minor = 10% of tumours occur here and 45% are malignant
Why is malignancy of the salivary glands said to be complex?
malignancy can arise from a variety of different stem cell lines within the glands.
What are benign epithelial neoplasms also known as?
adenomas
What are malignant epithelial neoplasms also known as?
adenocarcinoma
where are salivary gland neoplasia present in minor/intraoral salivary glands commonly found? (2)
Most common area:
- Junction of hard/soft palate
- Upper lip/cheek
When is a fine needle aspirate technique useful for testing swellings?
what is the limitation of this test?
salivary gland tumours/other swellings directly under the skin
only provides a small amount of tissue, not enough for proper diagnosis/understanding of the pathology, however is enough to alert the surgeon if it’s benign or malignant
What technique for biopsy is useful for intraoral swellings?
incisional biopsy
What is the name given to tumours which cannot be diagnosed?
Adenocarcinoma Not otherwise specified (NOS)
what is the most common type of (salivary) gland tumour?
Pleomorphic Adenoma:
= 75% of all salivary tumours
Can be a benign tumour of any gland tissue (not just salivary)
what salivary gland is most affected by a pleomorphic adenoma?
parotid
Describe what can be found histologically/pathologically in a pleomorphic adenoma. (4)
Varied - “mixed tumour” = Name comes for the variety of tissue appearances within the tumour
Duct like structures surrounded by (purple mesh) myoepithelial cells
has a connective tissue Capsule = variable and incomplete in a lot of cases
myxomatous tissue - soft and jelly like tissue
Why must patients be followed up for 5 years post removal of a pleomorphic adenoma? (3)
recurrence - multifocal = recurrence no. is more than the OG number
of tumours
commonly an Incomplete capsule = outgrowth of tumour growing into the surrounding tissues = high recurrence rate
- Recurrence esp higher in the minor salivary gland (as they have less complete capsules)
Myxomatous tissue:
- since its soft and jelly like its hard to remove and Any of this tissue left behind can give rise to another tumour
Progression to carcinoma (5%)
- The longer its present without removal = the higher the chances of it becoming malignant
How do we treat pleomorphic adenomas?
wide local excision
List the 3 distinctive factors in the pathology of a Warthins tumour.
– Completely encapsulated
– Recurrence is rare
– Malignant transformation rare
Describe the histology of a warthins tumour. (4)
– Cystic spaces present
- cystic spaced lined by 2x layers of pink epithelium and lymphoid tissue between
– Distinctive epithelium = oncocytic
– Can have germinal centres developing
How do we manage a warthins tumour?
excision
where is the highest proportion of salivary gland carcinomas found? (2)
in minor glands
sublingual gland
what areas/epithelium can give rise to a pleomorphic adenoma within the salivary gland? (4)
- Duct epithelium
- Myoepithelial cells (similar features to muscle cells, lie around the ducts)
- Myxoid areas (loose and gelatinous = hard to remove surgically)
- “chondroid” areas (appear similar to cartilage tissue formation)
what are the 2 main types of salivary gland carcinoma?
- Adenoid cystic carcinoma
- mucoepidermoid carcinoma
how do Adenoid cystic carcinomas present? (3)
- Slow growing
- Painless
- Nodule – then ulcerates and becomes painful as it progresses
What are the patterns of histology which can be seen in the adenoid cystic carcinoma? (3)
cribriform (“swiss cheese” – holy cheese)
tubular
solid
where can the adenoid cystic carcinoma spread to? (2)
how is it spread at a late stage?
local spread to nerves and bone
very infiltrative and grows by infiltration between the trabeculate of bones and along nerve fibres (perineural spread)
spreads late by metastasis via blood to lungs.
What are the problems associated with the adenoid cystic carcinoma? (3)
Difficult to treat/completely eradicate = poor prognosis
Very infiltrative – grows by infiltration between the trabeculate of bones and along nerve fibres (perineural spread)
Recurrence common
- long term prognosis is poor
What are the 2 cells types predominantly found in a mucoepidermoid carcinoma?
what does each form within the tumour?
- Glandular part which forms mucous
- Epidermoid/squamous cells – can form keratin within the tumour
where can mucoepidermoid carcinomas also be found? (not in salivary glands)
Intraosseous occurrence (from within the jaw) bone occasionally
where is the source within the jaw bone?
- Lesions (usually cystic) can be lined with odontogenic epithelium
- Odontogenic epithelium is multipotential = can form mucous cells
Describe the histology of a mucoepidermoid carcinoma.
- Mucous secretion cells present – show up with a special alcian blue stain (Mucous can spill out into the tissues and appear blue)
- Epidermoid cells
- Cystic spaces
- Necrotic areas
- Bleeding
- squamous epithelium
list other carcinomas which can be found in salivary glands.
- Acinic cell carcinoma
- Rare
- most found in the parotid
- Slow growing and less aggressive
- Histology varied, as is behaviour
- Polymorphous adenocarcinoma (more common)
- Occurs in Minor glands in palate
- Clinically and pathologically looks like adenoid cystic carcinoma, Immunohistochemistry may be needed to differentiate the two
- Better prognosis
- Slower growing
- Less metastasis
- Locally infiltrative (nerves)
where are most Acinic cell carcinomas found?
parotid
where are Polymorphous adenocarcinomas found?
minor glands in the palate
what tumour does the Polymorphous adenocarcinoma appear similar to clinically and pathologically?
how woudl we differentiate between the two?
adenoid cystic carcinoma,
Immunohistochemistry
