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
Prognosis for pleomorphic adenoma
Recurrence is main risk and risk of malignant transformation in longstanding lesions
Recurrence may be widely distributed within scar and difficult to manage
If becomes malignant - carcinoma ex pleomorphic adenoma
Warthin’s tumour
WHO definition
A tumour composed of glandular and often cystic structures, sometimes with a papillary cystic arrangement, lined by characteristic bilayered epithelium, comprising inner columnar eosinophilic or oncolytic cells surrounded by smaller basal cells.
The stroma contains a variable amount of lymphoid tissue with Germinal centres
Second most common salivary gland tumour
5-15% of all salivary gland tumours
Almost exclusively in the parotid
Presentation- 6th-7th decade
Clinically: doughy textured swelling
Slight male predominance
May be multifocal and bilateral
May be associated with other parotid tumours
Probably arises from ductal epithelium within parotid lymph nodes
Link with cigarette smoking-8x more risk
Microscopic features of Warthin’s tumour
Encapsulated - capsule generally thin/absent
Multicystic/papillary cystic lesion-honeycomb appearance
Cysts lined by bilateral oncolytic ductal epithelium
Lymphoid rich stroma with reactive follicles
Prognosis and management of Warthin’s tumour
Recurrence is uncommon
Most “recurrences” are actually new tumours (second primary) arising from adjacent normal parotid tissue
Malignant transformation is extremely uncommon
Complete excision- curative (usually superficial parotidectomy)
Oncocytoma
WHO definition
Benign tumour of salivary gland origin composed exclusively of large epithelial cells with characteristic bright eosinophilic granular cytoplasm (oncocytic cells)
Uncommon-2% of all salivary gland tumours
Mostly in parotid then submandibular then minor
6th-8th decade
Pathology: closely packed uniform plump cells with oncocytic cytoplasm (high mitochondrial content to stains bright on E &E sections)
Complete excision- curative
Malignant equivalent: oncocytic carcinoma- extremely rare and aggressive malignant tumour
Canalicular adenoma
WHO definition:
Tumour composed of columnar epithelial cells arranged in thin, anastomosing cords often with a beaded pattern. The stroma is characterized paucicellular and highly vascular
Uncommon benign tumour of minor salivary glands
Upper lip is the commonest site
4th-7th decade
May be multifocal within same gland
Pathology: bilayered strands basaloid cells, cords, beads on string appearance, loose fibro-vascular stroma
Conservative excision curative
Basal cell adenoma
WHO definition:
Rare benign neoplasm characterised by the basaloid appearance of the tumour cells and absence of myxochondroid stromal component present in pleomorphic adenoma
Uncommon
Mostly parotid gland, then submandibular
Elderly population mainly affected
Pathology: uniform basaloid cells, tubules, trabeculae, solid islands
NO chondomyxoid stroma
Complete excision- curative
Mucoepidermoid carcinoma
WHO definition:
Malignant glandular epithelial neoplasm characterised by mucous, intermediate and epidermoid cells, with columnar, clear cell and oncocytic features
Wide range of ages but common salivary gland malignancy in children and young adults
Peak in 2nd decade
Parotid gland - most common site followed by palate, submandibular, minor.
Can be central- intraosseoue- rare or in mandible
Microscopic features of mucoepidermoid carcinoma
Uncapsulated
Tumour infiltrates surrounding tissue and gland
Mucous filled cysts
Mucous cells
Epidermoid cells
Intermediate cells
Prognosis and management of mucoepidermoid carcinoma
Behaviour of malignancy variable and difficult to predict- microscopic grading important- low, intermediate, high grade
Low grade: cystic, lots of mucous cells
High grade: solid, few mucous cells, atypia, high mitoses, perineural invasion, infiltrative growth and necrosis
10 years overall survival rate
Low grade:90%
Intermediate grade:70%
High grade:25%
Adenoid cystic carcinoma
WHO definition:
Basaloid tumour consisting of epithelial and myoepithelial cells in variable morphologic configurations, including tubular, cribriform and solid patterns. It has a relentless clinical course and usually fatal outcome.
High grade malignancy
Median age 57 y
Account for less than 10% of all salivary gland tumours
Affects mostly major but less than a third occurs in minor
Presents with swelling/mass and may include numbness, paraesthesia, pain, involvement of motor nerves-facial, tongue weakness
Distal metastases- lung, bone, liver, brain
Lymph node spread is less common
Bone invasion without radiographic changes
Microscopic features of adenoid cystic carcinoma
3 patterns:
- Cribriform- multicystic islands with pseudocysts rich in GAGs, swiss cheese appearance
- Tubular- bilayered ducts
- Solid- solid aggregates of basaloid cells with little evidence of ductal differentiation- if more than 30% - high grade morphologically
Prognosis and management of adenoid cystic carcinoma
Surgery is treatment of choice- wide resection- usually extensive surgery needed
Clear margins difficult to achieve
Radiotherapy with wide fields
Chemotherapy generally not effective
Survival rate:50-70%
Factors influencing survival:
Tumour stage, node status, pt age, tumour site, large nerve perineural invasion, clear/not clear surgical margins
Polymorphous adenocarcinoma
WHO definition:
Malignant epithelial tumour characterised by cytologic uniformity, morphologic diversity, an infiltrative growth pattern and low metastatic potential.
Second most common intraoral malignant salivary gland
26% of all salivary gland tumours
50-70 age pattern
Palate is the commonest site, then buccal mucosa, retromolar region, upper lip, base of tongue
Mostly a malignancy of minor salivary glands but can occur in major salivary, lacrimal glandsz nasopharynx, nasal cavity
10% present with metastasis to lymph nodes
Microscopic features of polymorphous adenocarcinoma
Uncapsulated
1 cell type with wide range of patterns
Cells:
Uniform clear oval nuclei
Tiny pinpoint nucleoli
Minimal cytoplasm
Patterns:
Solid, cribriformz tubular single file, streaming cords, papillary, targetoid
Papillary types possibly show more aggressive behaviour
Perineural invasion common
May infiltrate bone of palate
Prognosis and management of polymorphous adenocarcinoma
Overall survival is generally good
Local recurrence 10-30%
Regional metastases:9-15%
Surgical excision with wide/clear margins is curative
Radiotherapy - its role not certain
Carcinoma ex pleomorphic adenoma
Pleomorphic adenoma from which an epithelial malignancy is derived
Usually arises from an untreated benign pleomorphic adenoma present for several years
Usually in parotid gland
Can arise from treated tumour that develops several recurrence over number of years
Presents as rapid swelling following an extremely long period of slow growth
Peak incidence 6th-7th decades
Microscopic features of carcinoma ex pleomorphic adenoma
Epithelial malignancy (mostly high grade adenocarcinomas) with a focus of normal appearing pleomorphic adenoma
Stromal scarring
Invasion through capsule into surrounding gland/CT
Extent of carcinoma component varies: intracapsular, minimally invasive, widely invasive
Prognosis and management of carcinoma ex pleomorphic adenoma
Extensive surgery with neck dissection is treatment of choice
Post op radiotherapy
Aggressive malignancy with local or distant metastases in 70% cases
5 year survival in 25-65%
More favourable outcome with intracapsular and minimally invasive carcinomas
Acinic cell carcinoma
Malignant epithelial neoplasm of salivary glands in which at least some of the neoplastic cells demonstrate serous acinar cell differentiation, which is characterized by cytoplasmic zymogen secretory granules. Salivary ductal cells are also a component of this neoplasm
Mean age of presentation: 50 y
Second most common salivary gland in children
90-95% in parotid
Typically present with slow growing solitary unfixed mass: 1/3 experience pain, some facial paralysis
Microscopic features of acinic cell carcinoma
Various cell types:
Acinic cells, intercalated duct(clear, non specific glandular)
Plump acinic cells with cytoplasmic zymogen granules are characteristic
Patterns:
Solid, microcytic, papillary follicular
It is considered as low/intermediate grade malignancy
Prognosis and management of acinic cell carcinoma
Complete excision is required
Generally not aggressive but some can metastasise to cervical lymph nodes and lung
Recurrence rate: 35%
20 year survival rate 90%
Prognostic factors include:
Large tumour size, involvement of parotid deep lobe, incomplete resection
Multiple recurrences and cervical lymph node and distant metastases predict poor prognosis
If high grade - shorter survival
