Salivary Gland Neoplasia Flashcards
Salivary gland anatomy
Major: parotid, submandibular, sublingual
Minor: present virtually on all mucosal surfaces in aerodigestive tract
Parotid gland
Largest of all glands
Positioned parotid bed anterior to ear overlying mandibular ramus
Lower pole extends into postauricular region
Intimately associated with facial nerve (CNVII)
It is serous glands- produces thin watery secretion via parotid duct- Stensen’s duct
Submandibular gland
Second largest salivary gland
Situated in submandibular triangle- associated with lower border of mandible, digastric and mylohyoid muscles and marginal mandibular branch of CNVII
Mixed serousmucous secretion-80% serous
Expresses secretions via submandibular duct into floor of mouth via Wharton’s duct
Sublingual gland
Smallest major gland
Located in submucosa of FOM
Nearby structures: submandibular duct, lingual nerve and lingual artery
Predominantly mucous
Expels secretions via Bartholin’s duct in FOM
Minor salivary glands
500-1000 in number
Located in almost every mucosal surface in head and neck region except attached gingivae and anterior hard palate
Predominantly mucous secretion
Salivary gland cell types
Acini: serous cells, mucous cells, mixed
Ducts:
Luminal cells: lying the lumen: can be cuboidal, columnar, squamous epithelium
Abluminar cells: surrounds luminal cells: myoepithelial and basal cells
- Intercalated and striated ducts are intralobular ducts
- Basal cells and luminal cells are ectralobular cells/forming extralobular ducts
What is neoplasia
A neoplasm is an abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of the normal tissues and persists in the same excessive manner after cessation of the stimuli which evoked the change
Can be malignant or benign
Salivary gland neoplasm
Rare (0,4-13,4/100 000)
3/100 000 in the UK
Peak at 6th-7th decade
Slightly commoner in women
75% are benign
Mostly affect major glands (80-85%)
Parotid- 90% of major gland tumours (submandibular 10% and sublingual rare)
Commonest parotid neoplasm is pleomorphic adenoma (60-70%)
Minor gland tumours (intraoral) are 15-20% of all salivary gland tumours
Palate: 55% of minor gland tumours
About 50% of minor gland neoplasms are malignant
Virtually all sublingual gland neoplasms are malignant
Aetiology of salivary gland neoplasm
Poorly understood
Radiation- nuclear bomb survivors, therapeutic radiation…
Tobacco smoking - not a risk in general but Wharton’s tumour is 8x more likely in smooers
Viruses: EBV and lymphoepithelial carcinoma
Familial and genetic
Various industrial occupations- rubber production, chemical industry
Benign Vs malignant salivary gland tumours
Benign:
Encapsulated, slow growing, rubbery consistency, mobile, overlying mucosa/skin appears normal, not invasive; incapable of metastasis, local excision is curative
Malignant:
Unencapsulated, rapid growth, dense, firm mass, fixed to underlying tissues, overlying skin/mucosa ulcerated, invades surrounding tissue including nerves (perineural invasion); cable of metastasis, requires more aggressive therapy (radiation +/- radiotherapy)
Investigators for suspected salivary gland tumours
Clinical history and examination
Imaging: radiography/sialography, ultrasound, CT, MRI
pathology: fine needle aspiration (takes cells rather than tissues, core biopsy -takes intact tissue- incisional or excisional)
If proven malignant: PT must be discussed as local MDT head and neck cancer meeting to determine course of treatment
Salivary gland neoplasms: classification
Epithelial tumours:
Benign:
Pleomorphic adenoma
Warthin’s tumour
Basal cell adenoma
Canalicular adenoma
Oncocytoma
Malignant:
Mucoepidermoid carcinoma
Adenoid cystic carcinoma
Polymorphous adenocarcinoma
Carcinoma ex pleomorphic adenoma
Acinic cell carcinoma
Non-epithelial
Lymphoma
Connective tissue tumours- lipoma…
Pleomorphic adenoma
WHO definition: tumour of variable capsulation characterised microscopically by ARCHITECTURAL rather than cellular pleomorphism. Epithelial and modified myoepithelial elements intermingle most commonly with tissue of mucoid, mucoid and chondroid appearance.
The most common tumour of major and minor glands in adults and children
Mostly in parotid
Wide age range: average 45 y
Most common 3rd-6th decade
Vary in size from few mm to few cm
3 main components of pleomorphic adenoma
Epithelial component:
Includes luminal ductal epithelium and myoepithelial cells (individual spindled cells distributed throughout stroma) arranged in bilayered ducts, tubules, ribbons and solid sheets
Connective tissue:
Myxoid, chondroid and dense fibrous tissue (usually no deposition of bone or fat within stroma)
Capsule:
Composed of dense fibrous tissue
- Discrete nodules of tumour can be present within of capsule- satellite nodules (important prognostic significance for recurrence
Management of pleomorphic adenoma
Wide surgical excision due to high rate of recurrence
Excision complicated by lobulated structure , presence of satellite nodules and loose myxoid consistency
Enucleation usually results in incomplete excision and recurrence
In parotid: superficial parotidectomy with preservation of facial nerve
In submandibular: resection of gland
In sublingual: wode local mucosal excision +/- bone