Dr Alpha Tsui Royal Melbourne Hospital 2008 - RCPA

Salivary gland cytology
Dr Alpha Tsui Royal Melbourne Hospital 2008
Approach to salivary gland lesions:
1. determine whether the lesion is indeed from the salivary gland. It may be from a
lymph node, skin lesion, soft tissue tumour, thyroid, etc
2. is it non-neoplastic or neoplastic ?
3. 1 cell or 2 cell population (epithelial, myoepithelial cells) ?
4. identify the predominant cell type: Basaloid, squamoid, oncocytic, clear cell,
sebaceous, spindled
5. identify background change and whether stroma-rich or stroma-poor: Lymphoid
background, mucin, hyaline globules / stromal matrix, cystic change
6. if neoplastic, is it benign, low grade or high grade malignancy ? (look at cellularity;
cohesiveness of the cells; degree of nuclear pleomorphism; chromatin pattern; N/C
ratio; nucleoli; cytoplasmic differentiation; stroma to cell ratio; mitoses; necrosis)
7. determine specific diagnostic features (precise subtyping of benign or malignant
lesions is usually not critical as there is little influence on subsequent management)
8. is the lesion primary or metastatic ? (requires clinical history; may need to do
immunostains on the cell block)
Morphological patterns:
Neoplasms with basaloid cells:
-basal cell adenoma / carcinoma
-adenoid cystic carcinoma
-cellular pleomorphic adenoma
-primary lymphoepithelioma-like carcinoma
-metastatic small cell carcinoma, Merkel cell carcinoma
-eccrine tumours, pilomatrixoma, basal cell carcinoma from overlying skin
-metastatic basaloid squamous cell carcinoma
-lymphoma
Neoplasms with squamoid cells:
-low grade mucoepidermoid carcinoma
-salivary duct carcinoma
-metastatic squamous cell carcinoma
-squamous metaplasia in Warthin's tumour and pleomorphic adenoma
Neoplasms with oncocytic cells:
-Warthin's tumour
-oncocytoma
-oncocytic carcinoma
-salivary duct carcinoma
-acinic cell carcinoma
-metastatic Hurthle cell carcinoma from the thyroid
-mucoepidermoid carcinoma (rarely)

Neoplasms with clear cells:
-clear cell oncocytoma
-myoepithelioma
-mucoepidermoid carcinoma
-acinic cell carcinoma
-epithelial-myoepithelial carcinoma
-clear cell adenocarcinoma
-metastatic clear cell carcinoma (e.g. from the kidney)
Neoplasms with sebaceous differentiation:
-sebaceous adenoma / lymphadenoma
-monomorphic adenoma
-pleomorphic adenoma
-Warthin’s tumour
-mucoepidermoid carcinoma
Lesions with spindled cells:
-non-specific fibrosis
-nodular fasciitis
-schwannoma
-myoepithelioma / myoepithelial carcinoma
-primary sarcomatoid carcinoma, sarcoma, carcinosarcoma
-metastatic carcinoma, melanoma
Lesions containing lymphocytes:
-chronic sialadenitis
-benign lymphoepithelial lesion
-lymphoepithelial cyst
-intraparotid lymph node
-Warthin's tumour
-sebaceous lymphadenoma
-acinic cell carcinoma
-mucoepidermoid carcinoma
-primary lymphoepithelioma-like carcinoma
-lymphoma
Lesions with mucin:
-mucocoele (rarely involving the parotid and submandibular glands)
-mucoepidermoid carcinoma
-mucinous adenocarcinoma
-pleomorphic adenoma (rarely)
Neoplasms with hyaline globules or fibrillary stromal matrix:
-pleomorphic adenoma
-basal cell adenoma
-adenoid cystic carcinoma (not seen in solid variant or poorly differentiated tumour)
-epithelial-myoepithelial carcinoma
-polymorphous low grade adenocarcinoma

Neoplasms with cystic change:
-Warthin’s tumour
-pleomorphic adenoma
-cystadenoma
-mucoepidermoid carcinoma
-acinic cell carcinoma
-cystadenocarcinoma
-metastatic e.g. cystic squamous cell carcinoma (commonly from nasopharynx)
Tumours with 2-cell population (epithelial and myoepithelial cells):
-pleomorphic adenoma
-basal cell adenoma / basal cell adenocarcinoma
-adenoid cystic carcinoma
-epithelial-myoepithelial carcinoma
Tumours with 1-cell population (epithelial or myoepithelial cells):
-myoepithelioma
-canalicular adenoma
-acinic cell carcinoma
-oncocytoma, oncocytic carcinoma
-polymorphous low grade adenocarcinoma
-salivary duct carcinoma
-clear cell adenocarcinoma
ADEQUACY: Sufficient diagnostic material. At least 2 passes (one dedicated for cell
block if likely to require immunostains e.g. difficult morphology, metastatic tumour,
lymphoma)
Normal salivary gland components:
-acinar tissue of serous or mucinous type, adipose tissue, ductal epithelium
-serous acinar cells show basophilic granular cytoplasm (Diff-Quik) with PASD
positive cytoplasmic granules; usually in lobulated spherical clusters
-mucinous cells are tall, columnar with abundant, finely granular or vacuolated
cytoplasm and basally located small round nuclei
-ductal cells seen as monolayered, cord-like or 3-D fragments
-ductal cells have scant cytoplasm and round to oval, small and dark nuclei
-myoepithelial cells are rarely seen as an isolated component in normal tissue and
they are closely associated with epithelial structures
-myoepithelial cells have oval to plasmacytoid shape, oval to round nuclei, moderate
amounts of cytoplasm or as bare nuclei
-other variable cell types: oncocytes (increase with age), metaplastic squamous cells,
sebaceous cells, lymphoid cells
Crystalloids:
-crystallised amylase common in cystic lesions of the parotid, appearing as rods,
squares, rectangles, needles, polyhedral shapes; non-birefringent (dark blue on Diff-
Quik, orange on Pap)
-collagenous crystalloids: usually seen in pleomorphic adenoma, appear as radially
arranged, needle shaped crystals (yellow or green with Pap)

-tyrosine-rich crystalloids may be seen in stromal component of pleomorphic
adenoma, adenoid cystic carcinoma, acinic cell carcinoma, low grade polymorphous
adenocarcinoma (flower-petal crystalline structures, often with 'sun-burst' appearance;
yellow-tan with Pap, blue with Diff-Quik; refractile; non-birefringent)
-cholesterol crystals
-calcium oxalate crystals
Specific entities:
Non-neoplastic cysts:
-water-like or viscous mucoid aspirate
-complete collapse of the cyst after aspiration
-histiocytes and other inflammatory cells
-epithelial cells - cuboidal and squamoid
Lymphoepithelial cyst:
-clear or turbid fluid (almost caseous-like material)
-inflammatory cells, macrophages, lymphocytes, immunoblasts, tingible body
macrophages, lympho-histiocytic aggregates, squamous cells, ciliated or mucinous
cells
-recognition of a nonlymphoid, epithelial squamous component is important
-squamous component consists of intermediate to superficial cells and numerous
anucleate squames
-multinucleated giant cells and cholesterol crystals are often present
-lack of oncocytes is a clue (present in Warthin's)
-wide maturational spectrum of lymphocytes seen (predominantly small and mature in
Warthin's)
Acute sialadenitis:
-may be bacterial / viral in aetiology or secondary to duct obstruction by calculi
-numerous neutrophils
-may see bacteria in the background
Chronic sialadenitis:
-scarcely cellular
-ductal epithelium in clusters and sheets
-scanty acinar groups with atrophy
-occasional fibroblasts, lymphocytes, neutrophils and macrophages
-beware squamous metaplastic cells which may show reactive atypia
Necrotising sialometaplasia:
-pools of mucus, inflammatory cells, metaplastic squamous cells showing moderate
reactive atypia
Features favouring necrotising sialometaplasia: necrosis, squamous cells,
typical site: palate, history of trauma.
Features against necrotising sialometaplasia: keratin debris, intermediate
cells, mucous-secreting cells, oncocytes.

Duct obstruction (by calculi):
-fibrosis and chronic inflammation
-squamous, mucinous and ciliated metaplasia
-may have abundant extracellular mucus, mimicking a mucoepidermoid carcinoma
-foreign body reaction with giant cells if duct rupture
Lymphoepithelial sialadenitis (benign lymphoepithelial lesion):
-cellular smears with lymphocytes, follicular centre cells, tingible body macrophages,
plasma cells and lympho-histiocytic aggregates
-tight groups of ductal and basal epithelial cells (rarely seen)
-may be mistaken for a lymph node if no epithelial cells are present
Intraparenchymal lymph node:
-reactive pattern with polymorphous population of lymphoid cells
-scant to absent epithelial component
Warthin's tumour:
-precipitate of thin-to-mucoid material containing a granular amorphous substance
and cellular debris
-monolayered sheets of oncocytic cells with distinct cell borders
-mixed population of lymphocytes often in aggregates
-the diagnosis of Warthin’s may be missed if the inflammatory cells predominate and
the oncocytes are difficult to see
-mast cells are seen within oncocytic clusters
Features favouring Warthin’s tumour: oncocytes, necrosis-like granular
background, lymphocytes, mast cells.
Features against Warthin’s tumour: intermediate cells; malignant
squamous cells; mucous-secreting cells.
Pleomorphic adenoma:
-aspirates have a thick, gelatinous consistency
-needs 3 components for the diagnosis: epithelial cells, myoepithelial cells, stroma
-ductal cells dispersed and in loosely cohesive groups, flat sheets, glands
-ductal cells are rounded, small, cuboidal with well-defined, sometimes eccentric
cytoplasm
-myoepithelial cells spindled or plasmacytoid; oval to round nuclei; moderate
amounts of cytoplasm or as bare nuclei
-clusters and single cells gradually merging with the mesenchymal elements
-fibrillary, myxoid stromal substance. May also show chondroid matrix.
-hyaline globules, tyrosine crystalloids and oxalate crystals may be present
-admixture of cellular and stromal components shows a characteristic blending, not
seen in other salivary gland tumours
-cystic change may occur: containing cellular debris, squamous as well as mucusproducing
cells
-oncocytic and squamous metaplasia can occur as potential pitfall
-beware occasional large stromal cells with multiple or multilobated bizarre nuclei,
probably representing a degenerative change

Problems with pleomorphic adenoma:
-matrix mistaken for mucus misdiagnosing as mucoepidermoid carcinoma
-cell-poor stroma-rich variant is a problem
-desmoplasia from other lesions may be mistaken for myxoid matrix
-squamous metaplasia, foam cells and cystic change may suggest mucoepidermoid
carcinoma
-morphology of pleomorphic adenoma (hyaline globules, basaloid cells) is quite
similar to that in polymorphous low grade adenocarcinoma or adenoid cystic
carcinoma
-atypical epithelial or myoepithelial cells
-predominantly spindled myoepithelial cells may suggest a sarcoma
-plasmacytoid myoepithelial cells may mimic a lymphoma or plasmacytoma
-cellular or matrix-deficient variant may resemble small blue cell tumours
Features favouring pleomorphic adenoma: ductal cells, myoepithelial
cells and chondromyxoid stroma all present.
Features against pleomorphic adenoma: mucous-secreting and/or
intermediate cells; lack of myoepithelial cells or chondromyxoid stroma.
Basal cell adenoma:
-cellular smear
-small clusters of branching cords, thick trabeculae, acini, single cells
-2 types of basaloid cells:
-larger oval to polygonal cells with round or oval nuclei, moderate amounts of
delicate pale cytoplasm (light cells – ductal)
-small oval cells with bland hyperchromatic nuclei and scanty cytoplasm; often
show palisading at the periphery of the groups (dark cells – myoepithelial)
-basosquamous whorling, keratin debris, keratinising squamous cells may be present
(absent in adenoid cystic carcinoma)
-may have extracellular homogeneous, hyaline, nonfibrillary and metachromatic
material at the edge of cell clusters
-thick bands of hyaline membrane outline individual nests
-collagenous stroma contains fibroblasts and capillaries
Features favouring basal cell adenoma: 2 types of basaloid cells, bare
nuclei, bland nuclear features.
Features against basal cell adenoma: necrosis, mitoses, tubular and fingerlike
structures, coarse chromatin.
Basal cell adenocarcinoma:
-marked cytological atypia including prominent nucleoli, mitoses, necrosis
-cells arranged in more 3-D multi-layered clusters
-diagnosis on cytology often difficult in low grade tumours, requiring demonstration
of local invasion on histology
Myoepithelioma:
-single cells or loosely cohesive sheets with slightly elongated spindled-shaped or
plasmacytoid cells, eccentric nuclei and inconspicuous nucleoli

-malignant myoepithelioma: marked atypia, necrosis, mitoses, intranuclear or
intracytoplasmic inclusions
Features favouring myoepithelioma: a pure population of plasmacytoid
or spindled cells; no chondroid matrix; no hyaline globules.
Features against myoepithelioma: mitoses; marked atypia; intranuclear
or intracytoplasmic inclusions.
Oncocytoma:
-clean or slightly bloody background
-cellular smear with oncocytes in 3D groups, sheets (multi-layered) and micro-acinar
structures
-round nuclei usually centrally located and containing distinct nucleoli
-cells show abundant granular, dense, non-vacuolated cytoplasm, sharp cytoplasmic
borders and cytoplasmic granules (blue on Diff-Quik; pink-orange on Pap)
-nuclear atypia may be prominent in benign cases
-absent lymphocytes and background debris
Features favouring oncocytoma: numerous isolated or clustered oncocytes.
Features against oncocytoma: lymphocytes, vacuolated cytoplasm,
numerous mitoses, chondromyxoid stroma, myoepithelial cells.
Oncocytic carcinoma:
-can be difficult to distinguish from oncocytoma with nuclear atypia
-more nuclear pleomorphism is seen
-mitoses, necrosis usually present
Adenoid cystic carcinoma:
-cellular smear
-crowded 3-D sheets, cribriform, acinar structures
-finger or cup-shaped groups an important feature
-small uniform cohesive basaloid cells with high N/C ratio, nuclear moulding, small
distinct nucleoli and minimal cytoplasm
-look for significant nuclear abnormalities including prominent nucleoli, enlarged
nuclear size, hyperchromasia and coarse chromatin (all these features may not present
in low grade tumours)
-lack of matrix in poorly differentiated or solid variant with only small cells may
mimic a small cell carcinoma
-presence of necrosis favours adenoid cystic carcinoma (seen in 50% of the cases)
2 types of extracellular material:
A) sheets of basaloid cells with microcystic spaces containing homogeneous acellular
hyaline globules or branching, cylindromatous hyaline material with basaloid cells
arranged around these cores
-these hyaline spheres (reduplicated basement membrane material) have a sharp
interface with the tumour cells
-this material is metachromatic (bright pink on Diff-Quik; light grey-blue with Pap)
-no myoepithelial cells embedded in the matrix

-the matrix can also be mucoid in appearance
B) desmoplastic stroma: does not form spheres or cylinders and interdigitates with the
tumour cells
Clear-cut malignant nuclear features are not seen in all the cases of
adenoid cystic carcinomas.
Features favouring adenoid cystic carcinoma: tubular, cylindrical and
cribriform structures, finger-like or cup-shaped cellular fragments.
Features against adenoid cystic carcinoma: chondromyxoid stroma, 3-D
basaloid clusters, clear cells.
Mucoepidermoid carcinoma:
-grading depends on cyst formation, ratio of stroma to epithelial cells and degree of
nuclear atypia
Low-grade:
-some tumours may only yield cyst fluid with a few mucous cells that are bland
-mixture of mucus-producing glandular cells with finely vacuolated cytoplasm,
intermediate and epidermoid (squamoid) cells in a mucoid background characteristic
-mucous cells may be histiocyte-like or resemble goblet cells
-intermediate cells have higher N/C ratio than epidermoid cells with darker ovoid
nuclei, small nucleoli and small amounts of cytoplasm (important component for the
diagnosis)
-epidermoid cells are non-keratinising with abundant cytoplasm
-background of mucus (stringy, not fibrillary), muciphages, lymphocytes, cholesterol
crystals. Keratinous debris is not a feature.
High grade:
-semisolid aspirate with numerous markedly atypical cells
-predominance of epidermoid cells and intermediate cells with scant mucus-producing
cells
Problems with mucoepidermoid carcinoma:
-can be sparsely cellular
-inflammation may predominate over epithelial cells
-cystic change with only a few “benign-appearing” cells
-low grade nuclear features
-may have sebaceous, clear cell or rarely oncocytic change
-high grade mucoepidermoid carcinomas may look like other high grade malignant
tumours
Any thick mucoid aspirate, even if sparsely cellular, should be suspicious for
mucoepidermoid carcinoma.
Features favouring mucoepidermoid carcinoma: intermediate cells, mucinsecreting
cells, mucoid background.
Features against mucoepidermoid carcinoma: plasmacytoid cells,
chondromyxoid stroma, marked keratinisation in the squamous cells and oncocytes.

Polymorphous low-grade adenocarcinoma (PLGA):
-site (minor salivary glands, esp. palate) and clinical history very important
-sheets, tight clusters, pseudopapillary and acinar structures
-small to medium-sized cells with scant to moderate cytoplasm
-uniform, finely granular nuclei with inconspicuous nucleoli and occasional nuclear
overlap
-dense and hyalinised stromal spheres an important component
-nuclei of adenoid cystic carcinoma show greater atypia than PLGA
-absent myoepithelial cells
Features favouring PLGA: polyhedral or oval cells in pseudopapillary
clusters, hyaline globules, typical site e.g. palate.
Features against PLGA: finger-like structures, chondromyxoid stroma.
Acinic cell carcinoma:
-bloody but otherwise 'clean' background
-cohesive 3-D sheets, clusters, sometimes with fibrovascular cores as well as acinarlike
groups and single cells
-tumour cells resembling normal acinar cells with slightly atypical nuclei with small
nucleoli and abundant cytoplasm
-cytoplasm is delicate with small vacuoles and containing larger PASD+ zymogen
granules (oncocytes have smaller granules and denser cytoplasm with no vacuoles)
-occasional bare tumour cell nuclei and single cells important feature
-nuclei stripped of cytoplasm may resemble lymphocytes and may potentially be
misdiagnosed
-features of acinic cell carcinoma as distinguished from normal: hypercellularity; acini
with loss of nuclear polarity; numerous bare nuclei; lack of ductal cells and fat.
-rare psammoma bodies in papillary cystic variant
Features favouring acinic cell carcinoma: cellular clusters of large acinar
cells, vascular cores, monotonous appearance, cytoplasmic vacuoles and zymogen
granules.
Features against acinic cell carcinoma: extensive necrosis, plasmacytoid cells,
oncocytes, squamous cells, chondromyxoid stroma.
Epithelial-myoepithelial carcinoma:
-characteristic bimodal population of large, clear, myoepithelial cells and small
cuboidal, hyperchromatic ductal cells, forming tubular, trabecular, pseudopapillary
structures
-background of stripped myoepithelial cell nuclei
-acellular, homogeneous, extracellular material surrounding cellular aggregates
-specific diagnosis is difficult if there is no biphasic pattern
-nuclear atypia is mild with most cells having enlarged oval nuclei and small nucleoli
-mitoses, apoptosis, necrosis uncommon

Features favouring epithelial-myoepithelial carcinoma: biphasic pattern
with darker central ductal cells and clear peripheral myoepithelial cells.
Features against epithelial-myoepithelial carcinoma: squamous cells,
chondromyxoid stroma, finger-like cellular fragments.
Salivary duct carcinoma:
-cells are arranged singly, in sheets or cohesive clusters
-cribriform areas, rosette-like aggregates, papillary architecture may be present
-large, polygonal, epithelial cells with moderate to abundant eosinophilic, granular
cytoplasm and large, hyperchromatic nuclei with prominent nucleoli (squamoid or
apocrine-like appearance)
-atypia ranges from mild (uncommon) to markedly pleomorphic
-extensive necrotic debris in the background an important clue
-psammoma bodies may be seen
Features favouring salivary duct carcinoma: granular cytoplasm, nuclear
atypia, mitoses, comedo-necrosis.
Features against salivary duct carcinoma: mucous-secreting cells, mucinous
background, squamous cells.
Cystic lesions containing squamous cells in the head and neck region:
-differential diagnosis:
-skin, subcutaneous lesions including epidermal, dermoid, sebaceous cysts, etc
-branchial cysts
-cystic squamous cell carcinoma (primary and metastatic)
-cystic salivary gland lesions with squamous cells e.g. mucoepidermoid carcinoma,
Warthin’s
-branchial cysts are generally seen in young patients and should never be diagnosed in
the elderly unless cystic squamous cell carcinoma has been excluded (usually
requiring excisional biopsy)
-malignant cells from a cystic squamous cell carcinoma can look relatively bland and
the aspirate is commonly hypocellular.
-in the fluid medium, the squamous cells are generally more rounded and appearing
“less pleomorphic” although neoplastic squamous cells often have aberrant shapes.
-features that favour malignancy include large tissue fragments, nuclear
pleomorphism, hyperchromasia and background necrosis. p53 staining in significant
numbers of cells favours a malignant process.
-the other potential problem is reactive squamous atypia in an actively inflamed
background. The chromatin pattern is open, vesicular and often with a central
nucleolus. The pyknotic nucleus of a parakeratotic squamous cell may also appear
“dark” but the overall size of the cell is very small.

FALSE POSITIVES:
-atypical features in pleomorphic adenoma
-reparative atypia in chronic or necrotising sialadenitis
-inflammation with reactive atypia, mucin strands and squamous metaplasia,
mimicking a mucoepidermoid carcinoma
-radiation atypia
FALSE NEGATIVES:
-cystic lesions e.g. mucoepidermoid carcinoma with predominantly mucin and scanty
tumour cells
-well-differentiated tumours e.g. acinic cell carcinoma, low grade mucoepidermoid
carcinoma
-only the benign component is sampled in a carcinoma ex pleomorphic adenoma
-low grade lymphoma
-lymphoepithelial sialadenitis transforming to lymphoma
PRACTICAL TIPS:
1. Many lesions may be complicated by cystic degeneration, inflammation, clear cell
change or metaplasia.
2. Hyaline globules are not specific for adenoid cystic carcinoma. May be seen in
other tumour types. Solid or high grade adenoid cystic carcinoma does not contain
significant matrix material, making diagnosis difficult.
3. Fibrous stroma from chronic sialadenitis can mimic myxoid matrix of a
pleomorphic adenoma. The former is a pauci-cellular lesion with scattered
inflammatory cells. There are no ductal or myoepithelial cells as in pleomorphic
adenoma.
4. If a cystic lesion contains mucin, always suspect low-grade mucoepidermoid
carcinoma.
5. If well-differentiated keratinised malignant squamous cells predominate, beware
metastatic squamous cell carcinoma (from ENT sites). Mucoepidermoid
carcinoma does not usually contain well-keratinised neoplastic squamous cells.
6. Loss of normal lobulated arrangement in acinar cells may raise suspicion of
malignancy (well-differentiated acinic cell carcinoma).
7. Enlargement of a few epithelial cells in an otherwise typical pleomorphic
adenoma does not indicate malignancy. However, if the atypical cells are
numerous forming substantial aggregates and are adjacent to bland epithelial cells

typical of pleomorphic adenoma, a carcinoma ex pleomorphic adenoma should be
suspected.
8. Beware cystic lesion with squamous cells in the elderly, look carefully for features
of squamous cell carcinoma (may represent a metastasis in a lymph node with
cystic necrotic change). Branchial cysts are rare in the elderly. Recommend
excision, even if the squamous cells look “bland”.

Fig 1. Normal acinar cells in a lobule.
Fig 2. Lymphoepithelial sialadenitis with a small cluster of epithelial cells and a
background of mature lymphocytes.

Fig 3. Warthin’s tumour with oncocytes.
Fig 4. Warthin’s tumour with oncocytes.

Fig 5. Oncocytoma. Tumour cells have granular cytoplasm. No lymphocytes in the
background.
Fig 6. Oncocytic carcinoma. Tumour cells have malignant nuclear features and
granular cytoplasm.

Fig 7. Pleomorphic adenoma with epithelial and stromal components.
Fig 8. Pleomorphic adenoma with epithelial cells, forming ductal structures.

Fig 9. Pleomorphic adenoma. Fibrillary myxoid stroma.
Fig 10. Spindled myoepithelial cells in the myxoid stroma.

Fig 11. Carcinoma ex pleomorphic adenoma. Note tumour cells with malignant
nuclear features.
Fig 12. Basal cell adenoma, forming intersecting thick trabeculae.

Fig 13. Basal cell adenoma. Peripheral palisading of the cells.
Fig 14. Basal cell adenoma. Thickened basement membrane material around a nest.

Fig 15. Basal cell adenoma. Note: Bland tumour cells.
Fig 16. Mucoepidermoid carcinoma. Note mucous cells (Arrow).

Fig 17. Mucoepidermoid carcinoma with abundant epidermoid cells.
Fig 18. Mucoepidermoid carcinoma. Intermediate cells with higher N/C ratio (red
arrow). Epidermoid cells with lower N/C ratio (yellow arrow).

Fig 19. Adenoid cystic carcinoma with elongated groups and single cells.
Fig 20. Adenoid cystic carcinoma. Finger-like and bowl-shaped cell groups.

Fig 21. Adenoid cystic carcinoma with a cribriform structure.
Fig 22. Adenoid cystic carcinoma. Note hyaline globules.

Fig 23. Adenoid cystic carcinoma with cylindromatous hyaline material, surrounded
by tumour cells.
Fig 24. Adenoid cystic carcinoma with basophilic mucoid matrix material.

Fig 25. Adenoid cystic carcinoma. Note tumour cells with angulated nuclei.
Fig 26. Acinic cell carcinoma.

Fig 27. Acinic cell carcinoma with papillary groups and single cells.
Fig 28. Acinic cell carcinoma. Tumour cells with enlarged round nuclei, granular and
vacuolated cytoplasm.

Fig 29. Salivary duct carcinoma.
Fig 30. Branchial cyst with squamous cells and marked inflammation in a young
patient.

Fig 31. Metastatic squamous cell carcinoma to a parotid lymph node. This degree of
keratinisation is not seen in a mucoepidermoid carcinoma. Also the tumour cells can
look rather bland.
Fig 32. Pilomatrixoma with basaloid cells, resembling a basaloid salivary gland
neoplasm.

Fig 33. Pilomatrixoma with shadow squamous cells - important diagnostic feature.

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