Week 12 - Salivary Glands Flashcards
Major Salivary Glands
Parotid, submandibular and sublingual glands
Macroscopically discrete glands, may be palpable especially in pathologic states
Minor Salivary Glands
Microscopic collections of 800-1000 small salivary glands of acini and ducts within upper aerodigestive tract mucosa (E.g. tongue, palate, tonsil etc)
Not normally seen on imaging
Why is Production of Saliva Important?
Lubrication: moistens oral mucosa, moistens and
cools food
Digestion: Amylase and Lipase
Immunity: Lysozyme, IgA
Histology of Salivary Glands
Acini – lined by luminal cells
- serous: central lumen with PAS+ secretory granules containing amylase
- mucinous: irregular pattern, abundant cytoplasm, clear mucin, PAS+ sialomucins
Myoepithelial cells – surround acini and mediate contraction
Ducts
Stroma
- fibrocollagenous tissue
- adipose tissue
- blood vessels and nerves
Milan Reporting System
Non-Dx (1)
- risk of malignancy: 25%
- management: clinical and raiological FU/Rpt FNA
Non-neoplastic (2)
- risk of malignancy: 10%
- management: clinical FU and radiological correlation
Atypia of US (AUS) (3)
- risk of malignancy: 20%
- management: rpt FNA or surgery
Neoplasm - Benign (4)
- risk of malignancy: <5%
- management: surgery or clinical FU
Neoplasm - SG or SUMP (4)
- risk of malignancy: 35%
- management: surgery
Suspicious for malig (5)
- risk of malignancy: 60%
- management: surgery
Malignant (6)
- risk of malignancy: 90%
- management: surgery
FNA vs Core Biopsy in Salivary Glands
Lower complication rate with FNA
Potential risk of contaminating surgical planes with core bx
Clinical Details Required
Age
Site (exact dx site*)
Size
Duration
Associated symptoms e.g. facial pain, paraesthesia
PMHx
Imaging characteristics
Non-Neoplastic Head and Neck Salivary Gland Overview
Branchial cysts - lump in the neck
Can develop rapidly as a firm mass of significant size usually in neck
Seen in any age
DDx malig cervical node/SG neoplasm
Aspirate resembles pus/inflamed cyst
Non-Neoplastic Head and Neck Salivary Gland Cytology
Anucleate keratinised sq cells
Squamous epithelial cells, mainly mature, metas+/-
Bg of amorphous debris and inflammatory cells
Malignant SG Neoplasms
Likelihood of malignancy inversely proportional to size of glands
- rule of thumb: 25/50/75
80-90% of salivary gland neoplasms occur in the floor of mouth, tongue and retromolar region are malignant
What to Look for When Evaluating SG FNA Smears
Cellularity
Background
- characteristic matrix, mucin?
- inflammation, debris, stones, fragments
- lymphoid infiltrates
Cell types
- ductal
- myoepithelial: spindled, plasmacytoid, clear cells
- acinar
- squamous, oncocytic, sebaceous, mucinous etc.
Diagnostic Categories
Normal
Non-Diagnostic
Benign
Atypical/Primary salivary gland neoplasm
Suspicious for malignancy
Malignant
Diagnostic Challenges: Cystic Lesions
Potential for false negative results due to low cell yield
Chronic sialadenitis with mucinous metaplasia vs mucoepidermoid carcinoma
Re-aspirate residual mass after cystic fluid drainage
Low threshold for recommending excision of cystic lesion with mucinous background
Diagnostic Challenges: Benign vs Low Grade Malignant Neoplasms
Overlapping cytologic features
- e.g. cellular PA vs Polymorphous low grade adeno
- absence of overt cytologic atypia
- unable to assess infiltrative growth pattern on cytology
Local excision generally appropriate for both
Use pragmatic category “Primary salivary gland neoplasm” no overt high grade features
Diagnostic Challenges - High Grade Malignancy
Primary vs metastases
Epithelial vs other (lymphoid, mesenchymal etc)
Radical surgery +/- neck dissection vs systemic therapy
**Adequate clinical history
Immunohistochemical stains on CB and other ancillary tests e.g. Flow Cytometry etc. **
Non-Dx FNA SG
Sampling error
Insufficient material
- normal salivary gland components only
- generally low cellularity smears
- acinar cells form rounded clusters
- ductal cells form flat sheets and tubules
Chronic Sialadenitis
Küttner’s tumour- IgG4 Auto immune disorder
Smears often scanty, with ductal cells and smaller nos of acinar cells
Bg of bare oval nuclei of acinar epithelial cells, lymphoid infiltrate
Chronic Sialadenitis with Mucinous Metaplasia
Mucinous bg
Ciliated columnar cells
Stone fragments
Absence of mucus secreting and epidermoid cells
DDx of Squamous Lined Cystic Lesions - Non-Neoplastic Cyst
Branchial cleft cyst, lymphoepithelial cysts
Simple cysts - lined by sq epith are RARE in SG
DDx of Squamous Lined Cystic Lesions - Primary Neoplasm with Cystic Component
Warthin’s tumour with squamous metaplasia
PA with squamous metaplasia
Mucoepidermoid carcinoma
Acinic cell carcinoma
Pleomorphic Adenoma
Occurs in all ages, major and minor SG
Cytological dx usually straightforward in classical cases
Benign behaviour
Treatment is complete surgical excision
Pleomorphic Adenoma - Cytology
Background of stroma
- classically magenta in colour, fibrillary and magenta in appearance on DQ
- may have mucin, basement membrane, hyaline globules
Myoepithelial cells
- plasmacytoid (common) - ovoid or spindle with abundant well defined cytoplasm
- spindled
Ductal cells - regular ovoid nuclei with bland finely granular nuclear chromatin and smooth nuclear membranes
May have metaplastic cells, oncocytic cells, goblet cells, sebaceous or squamoid appearance
Where are Hyaline Globules and Basement Membrane Material Found?
Pleomorphic adenoma
Basal cell adenoma
Adenoid cystic carcinoma
Basal cell adenocarcinoma
Polymorphous low-grade carcinoma
Warthin’s Tumour
Mainly lower pole parotid and upper cervical nodes
May be bilateral and multiple
M > F, 6th decade; associated with smoking hx
Aspirate is typically cystic (Clear or Brown, can appear mucoid,
murky)
Warthin’s Tumour Classic Cytology
Uniform sheets of bland oncocytic cells, monolayered appearance
Cystic debris
Background mixed lymphoid cells, amorphous and granular debris
Mast cells commonly assoc with oncocytic cells
Warthin’s Tumour - Pitfalls
Squamous metaplasia
- if extensive, features may be easily misinterpreted as cavitating SCC
- honeycomb sheets of oncocytes and singly scattered columnar shaped cells are helpful pointers for WT
Mucoid background
- DDx mucoepidermoid carcinoma
Oncocyte-rich neoplasms
- DDx oncocytoma, oncocytosis, acinic cell ca
Lymphocyte-rich
- DDx intraparotid lymph node, lymphoepithelial sialadenitis
