OP20 Neoplastic diseases of the salivary glands

Question 1

Already uncommon, but where are salivary gland tumours most commonly found?

Answer 1

Major more than minor
Parotid mostly
Palate mostly for minor
Major gland tumours are mainly benign. The malignant tumours are mainly in minor glands - mostly palate and tongue.

Question 2

What is the multicellular theory for the arisal of salivary gland tumours?

Answer 2

All cell types can proliferate: serous and mucous acinar cells, ductal, basal cells, myoepithelial cells. Histological makeup of tumour depends on the proliferating cells.

Question 3

What are the main of the benign salivary gland tumours? (7)

Answer 3

Pleomorphic adenoma
Myoepithelioma
Warthin tumour
Basal cell adenoma
Oncocytoma
Canalicular adenoma
Ductal papillomas

Question 4

What are most of the salivary gland carcinomas?

Answer 4

Mucoepidemoid ca.
Acinic cell ca.
Adenoid cystic ca.
Carcinoma ex-pleomorphic adenoma
Polymorphous low-grade adenocarcinoma
Adenocarcinoma NOS

Question 5

What is the commonest salivary gland tumour?

Answer 5

Pleomorphic adenoma

Question 6

When does pleomorphic adenoma mainly present?

Answer 6

5-6th decades, females

Question 7

Clinically how does pleomorphic adenoma act?

Answer 7

Slow growing, painless, rubbery swelling

Question 8

What is the histology of pleomorphic adenoma?

Answer 8

May be encapsulated, incompletely
Varied epithelial and stromal patterns (pleomorphic): epithelial and myoepithelial cells forming sheets, strands, ducts in a myxoid/mucoid, chondroid or fibrous stroma
Plasmacytoid pattern, squamous metaplasia

Question 9

Can pleomorphic adenomas transform?

Answer 9

Benign, but may transform

Question 10

Which type of pleomorphic adenoma are most likely to recur?

Answer 10

Myxoid neoplasms more likely to recur

Question 11

What does plasmacytoid mean?

Answer 11

Nucleus is eccentric, looking towards one side of the cell

Question 12

What is myoepithelioma?

Answer 12

Rare tumour of myoepithelial cells
More common in 5th decade females

Question 13

Where does myoepithelioma occur?

Answer 13

Minor salivary glands, primarily palate, parotid

Question 14

What is the histology of myoepithelioma?

Answer 14

Most solid pattern, spindle cells, plasmacytoid pattern, epithelioid and clear cells, no ductal structure, S-100 protein positive

Question 15

Where does Warthin tumour (adenolymphoma) occur?

Answer 15

Parotid

Question 16

What is the origin of Warthin tumour/adenolymphoma?

Answer 16

Salivary duct epithelium entrapped in lymph nodes

Question 17

What is the histology of Warthin tumour/adenolymphoma?

Answer 17

Glandular, often multiple cystic structures (papillary) lined by eosinophilic epithelium (2 layers, cuboidal and columnar, rich in abnormal mitochondria) + stroma with lymphoid tissue

Granular eosinophilic cells are composed of luminal columnar cells with hyperchromatic nuclei aligned toward the luminal aspect and basal cuboidal cells with vesicular nuclei

Question 18

What does papillary mean?

Answer 18

Small raised structure - has ins and outs

Question 19

Where do basal cell adenomas usually occur?

Answer 19

Parotid mainly, then upper lip

Question 20

How do basal cell adenomas present?

Answer 20

Uniform, prominent basaloid cells, basement membrane-like structure, no mucoid stroma
Encapsulated
Patterns: solid, trabecular, tubular & membranous

Question 21

What can basal cell adenoma transform into?

Answer 21

Basal cell adenocarcinoma

Question 22

What is the histology of basal cell adenoma?

Answer 22

Solid type - Nests of basaloid cells with peripheral palisading
Membranous type - nests of basaloid cells surrounded by a distinct hyaline band
Trabecular type - thick chains of basaloid cells in a loos fibrous stroma

Question 23

What are oncocytes?

Answer 23

Abnormal mitochondria
Polygonal cells with abundant granular eosinophilic cytoplasm and round, centrally placed nuclei, with or without nucleoli

Question 24

Where does oncocytoma usually occur?

Answer 24

Parotid

Question 25

What is the histology of oncocytoma?

Answer 25

Polyhedral faintly granular eosinophilic cells (oncocytes) with small dark nuclei Solid, trabecular or tubular patterns

Question 26

What might oncocytoma be difficult to distinguish from?

Answer 26

Oncocytic hyperplasia - an aging change

Question 27

What is the histology of canalicular adenoma?

Answer 27

Columnar epithelial cells arranging in anastomosing bi-layer strands (beading pattern) Loose, highly vascular stroma

Question 28

Where are ductal papillomas from?

Answer 28

(rare) From excretory ducts

Question 29

What are the 3 types of ductal papillomas?

Answer 29

Inverted ductal papilloma: endophytic. Intraductal papilloma: exophytic Sialadenoma papilliferum: exophytic and endophytic (exo and endophytic with regard to duct structure)

Question 30

What might ductal papillomas mimic?

Answer 30

Sialethiasis eg calculus formation in duct, or neoplasm etc

Question 31

What is the histology of inverted ductal papilloma?

Answer 31

Bulbous endophytic growth arising from a duct Cuboidal-to-columnar cells seen on luminal surface with scattered mucous cells

Question 32

What is the histology of intraductal papilloma?

Answer 32

Luminal papillary proliferation Well-organised papillary structures with fibrovascular cores and microcysts

Question 33

What is the histology of sialadenoma papilliferum?

Answer 33

Adenomatous proliferation with papillary hyperplasia Luminal cells are cuboidal with spindled nuclei and there is a subtle cribriform architecture Surface papillary squamous proliferation and adenomatous proliferation of ducts at base

Question 34

What is the commonest malignant salivary gland tumour?

Answer 34

Mucoepidermoid carcinoma

Question 35

Where are mucoepidermoid carcinomas found?

Answer 35

Parotid then palate Low grade carcinoma of major glands

Question 36

What is the histology of mucoepidermoid carcinoma?

Answer 36

Poorly circumscribed, invasive, cystic formation cell, 3 cell types

Question 37

What is the histology of the 3 cell types of mucoepidermoid carcinoma?

Answer 37

Squamous/epidermoid cells: intercellular bridges, keratinisation very rare, solid or cyst lining Mucus producing cells: cuboidal-columnar-goblet, solid or cyst lining, mucin production (PAS), cyst might break inducing a granulomatous reaction Intermediate cells: small, dark stained nuclei

Question 38

What is the 5yr survival for low and high grade mucoepidermoid carcinomas?

Answer 38

Low grade - 90% (cystic, >50% mucous cells, more circumscribed) High grade - poor (squamous and intermediate cells, haemorrhage and necrosis areas)

Question 39

What is acinic cell carcinoma - where is it found, what grade, how does it present?

Answer 39

Majority in parotid Low grade Multinodular, solid or cystic

Question 40

What is the histology of acinic cell carcinoma?

Answer 40

Sheets/groups of large, polygonal acinar cells with granular cytoplasms (PAS+), vacuolated cells, intercalated duct-like cells, lymphoid infiltrate in the stroma Shows some cytological differentiation towards acinar cells, but a wide range of histopathological patterns: solid, microcystic, papillar-cystic, follicular

Question 41

Where are adenoid cystic carcinomas most common and how do they present?

Answer 41

Minor SGs Slow enlarging, pain, ulceration, facial palsy in parotid Aggressive, infiltrative

Question 42

What are the 3 histological patterns of adenoid cystic carcinoma?

Answer 42

Cribriform pattern, basement membrane-like material Tubular, surrounded by desmoplastic stroma (producing lots of fibrous tissue) Solid

Question 43

What are the 2 cells types in adenoid cystic carcinoma?

Answer 43

Duct lining cells (small basophilic) forming pseudo/cysts and myoepithelial cells.

Question 44

Neurotropism can occur in adenoid cystic carcinoma. What is this?

Answer 44

Perineural and perivascular invasion without stromal reaction, in bone spreads via marrow spaces (bad prognosis)

Question 45

What can neurotropism cause?

Answer 45

If affecting sensory nerves can cause pain, or motor nerves can disturb function.

Question 46

What is carcinoma ex-pleomorphic adenoma? (uncommon)

Answer 46

Arises from pleomorphic adenomas (mostly parotid) which have been present a long time leading to adenocarcinoma or undifferentiated carcinoma Mostly around 10yrs after pleomorphic adenoma

Question 47

What is the prognosis of carcinoma ex-pleomorphic adenoma?

Answer 47

If still inside the capsule of a PA (in situ), good prognosis, otherwise poor. Can metastasise to lymph nodes, lungs, bones.

Question 48

Where does polymorphous low-grade adenocarcinoma occur?

Answer 48

Minor SG in the palate

Question 49

Give some features of polymorphous low-grade adenocarcinoma

Answer 49

Various growth patterns (lobular, papillary, cribriform, trabecular) Neurotropism (concentric) induces mucinosis in the stroma Unpredictable prognosis

Question 50

What are differential diagnoses for polymorphous low-grade adenocarcinoma?

Answer 50

Adenoid cystic carcinoma (hyperchromatic nuclei, more infiltrative) Pleomorphic adenoma (myochondroid/chondroid stroma)

Question 51

What is adenocarcinoma NOS?

Answer 51

NOS = not otherwise specific Tumours that do not fit into recognised types Usually in parotid, 6th decade, females

Question 52

What do adenocarcinoma NOS usually present like?

Answer 52

Infiltrating neoplasms, showing some glandular or ductal structures

Question 53

How are adenocarcinoma NOS graded?

Answer 53

Graded according to duct number and epithelial atypia: few ducts and solid high grade

Question 54

What is the prognosis of salivary gland tumours?

Answer 54

Stage (size) is perhaps more important than grade: 4cm rule (T1 or T2) <4cm have a much higher 5yr survival than >4cm Risk of distant metastases is much large in the >4cm