Salivary glands

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The salivary glands help digest food. ENT surgeons take 'em out and want you to diagnose 'em. Cytopathology of the salivary glands is covered in the Head and neck cytopathology article.

Normal

Types of salivary glands

Types of glands:[1]

  1. Serrous - eosinophilic cytoplasmic granules, acinar arrangement - vaguely resembles the acinar morphology of the pancreas.
  2. Mucinous - light eosinophilic staining.

Identifying the glands

The three main glands:

  1. Parotid:
    • Serous glands - lower viscosity, acini (lobules).[2]
    • Most tumours in this gland are benign.
  2. Submandibular:
    • Serous and mucinous glands.
      • Serous ~90% of gland.
      • Mucinous ~10% of gland.
  3. Sublingual:
    • Mucinous glands.

Other:

  • Adipose tissue is found between the glands.
    • It increases with age.

Images:

Memory devices:

  • The parotid gland vaguely resembles the pancreas.
  • Submandibular = glands are mixed.

Overview

Benign tumours

Tabular form - adapted from Thompson[3]

Architecture Morphology Cell borders Cytoplasm Nucleus DDx Other Image
Pleomorphic adenoma var. mixed pop.; must include: (1) myoepithelium, (2) epithelium (ductal cells), (3) chondromyxoid stroma var. var. (1) plasmacytoid adenoid cystic c. occ. encapsulated,
mixed pop. of glandular,
myoepithelial and mesenchymal cells 		[1]
Warthin tumour papillary,
bilayer 		cuboid (basal), columnar (apical) clearly seen eosinophilic, abundant unremarkable sebaceous lymphadenoma AKA papillary cystadenoma lymphomatosum [2], [3]
Basal cell adenoma var., islands surrounded
by hyaline bands 		basaloid subtle scant,
hyperchromatic 		granular basal cell adenoca - -
Canalicular adenoma chains of cells cuboid or columnar subtle scant,
hyperchromatic 		granular basal cell adenoma IHC: p63- -
Sialoblastoma var., islands surrounded
by loose fibrous stroma 		basaloid subtle scant, hyperch. granular basal cell adenoca - -

Malignant tumours

Tabular form - adapted from Thompson[4]

Architecture Morphology Cell borders Cytoplasm Nucleus DDx Other
Mucoepidermoid carcinoma cystic & solid epithelioid distinct fuffy, clear,
abundant 		nuclei sm. ? IHC: p63+
Acinic cell adenocarcinoma (AcCC) acinar (islands) epithelioid clear granular, generous stippled, +/-occ. nucleoli ? ?
Adenoid cystic carcinoma (AdCC) pseudocysts,
cribriform, solid,
hyaline stroma 		epithelioid subtle scant,
hyperchromatic 		small
"carrot-shaped" 		? ?
Salivary duct carcinoma glandular, cribriform columnar subtle/clear hyperchromatic columnar metastatic breast ca similar to ductal
breast carcinoma
Polymorphous low-grade adenocarcinoma variable, often small
nests, may be targetoid 		epithelioid indistinct eosinophilic ovoid & small with
small nucleoli 		? minor salivary gland tumour,
often in palate,
cytologically monotonous; IHC: S100+, CK+, vim.+, GFAP+/-, BCL2+/-

DDx by site

Palate:

  • Polymorphous low-grade adenocarcinoma.
  • Adenoid cystic carcinoma.
  • Pleomorphic adenoma.

Benign

General DDx:

  • Inflammation.
  • Neoplasm.
  • Ductal obstrution.

Chronic Sialadenitis

General

Etiology:[5]

Microscopic

Features:

  • Fibrosis.
  • Non-neoplastic mononuclear inflammatory infiltrate.

Image:

Mucocele

Microscopic

Features:

  • Mucous.

Pleomorphic adenoma

Epidemiology

Features:[6]

  • Very common - approx. 60% of parotid gland tumours

Histology

Features:[6]

  • Proliferation of myoepithelium and epithelium in mesenchymal stroma.
  • Mesenchymal stroma - key feature.
    • May be any of following: myxoid, mucochondroid, hyalinized, osseous, fatty.
  • Look for, i.e. rule-out, poorly differentiated carcinoma: carcinoma ex pleomorphic adenoma.

IHC: S-100 +ve, SMA +ve, GFAP +ve.

Basal cell adenoma

General

  • ~2% of salivary gland tumours.
  • May be multifocal.
  • Usu. parotid gland, occasionally submandibular gland.

Microscopic

Features:

  • Basophilic cells.
  • Usu. nests; may be bilayed tubules or trabeculae.

Notes:

  • No chondromyxoid stroma.
    • Chondromyxoid stroma present -> pleomorphic adenoma.
  • Neoplastic cells embeded in stroma ("stromal invasion") = basal cell adenocarcinoma.
    • Basal cell adenocarcinoma may be cytologically indistinguishable from basal cell adenoma, i.e. "bad" architecture makes it a basal cell adenocarcinoma.

IHC

  • Luminal stains +ve: CK7 +ve, CAM5.2 +ve.

Canalicular adenoma

Microscopic

Features:

  • Channels.

Papillary cystadeoma lymphomatosum

  • AKA Warthin tumour.
  • Papillae.

Microscopy

  • Papillae (nipple-shaped structures) with a two rows of pink (eosinophilic) epithelial cells (with cuboidal basal cells and columnar luminal cells) -- key feature.
  • Fibrous capsule - pink & homogenous on H&E.
  • Cystic space.
  • Lymphoid stroma.

DDx

  • Lymphoepithelial cyst.
    • Cyst within a lymph node.

Sebaceous adenoma

Features:

  • Benign counterpart of sebaceous carcinoma.

Oncocytoma

Features:

  • Like oncocytomas elsewhere.
    • Eosinophilic cytoplasm (H&E) - due to increased number of mitochrondria.

Malignant

Approach:

  • Differentiate -- luminal vs. myoepithelial vs. basal.

Mucoepidermoid carcinoma

General

  • Most common malignant neoplasm of salivary gland.

Microscopic

Features:

  • Abundant fluffy cytoplasm - with large mucin vacuoles - key feature.
  • Nucleus distorted by mucin vacuole.
  • Architecture:[7]
    • Cystic - low grade.
    • Solid - high grade.

Notes:

  • Mucin vacuoles may be rare; in a superficial glance -- it may mimic squamous cell carcinoma.

Images:

Acinic cell adenocarcinoma

  • Abbreviated AcCC.
  • Common malignant neoplasm of salivary gland.

Features:

  • Psammoma bodies(?).
  • Abundant cytoplasm.
  • Stipled chromatin.
  • Acinar architecture (islands of cells).

Memory device:

  • AcCC - lots of "C"s - chromatin stipled, cytoplasm generous.

Adenoid cystic carcinoma

General

  • Common malignant neoplasm of salivary gland.
  • AKA cylindroma.[8]
    • Should not be confused with dermal cylindroma (a benign skin tumour).

Microscopic

Features:

  • Cribriform architecture.
  • Scant cytoplasm.
  • Carrot-shaped nucleus.
  • Hyaline stroma.

Images: Adenoid cystic carcinoma - Mod. Pathol.

Memory device:

  • AdCC - mostly DNA (scant cytoplasm), distinct nucleus (carrot-shaped).

IHC

Features:[9]

  • CD117 +ve.
  • Cyclin D1 +ve.

Salivary duct carcinoma

Needs work.

  • Malignant counterpart of salivary duct adenoma.

Polymorphous low-grade adenocarcinoma

  • Classically found in the palate.
  • Tumour of the minor salivary glands.

Microscopy

  • Cytologically monotonous (uniform) with variable architecture - key feature.
    • Architecture: often small nests, may be targetoid.
  • Nucleus: ovoid & small with small nucleoli.
  • Indistinct cell borders.
  • Eosinophilic cytoplasm.

DDx

  • Pleomorphic adenoma.
  • Adenoid cystic carcinoma.

Carcinoma ex pleomorphic adenoma

  • Malignant transformation of pleomorphic adenoma.
  • Rare.
  • May be subtle.

Microscopy

  • Nests of cells, may from glands, single cells. (???)

Note:

  • Adenocarcinoma-like.

Sebaceous carcinoma

  • Arises from sebaceous glands
  • Sebaceous glands are serous glands and clear on H&E.

See also

References

  1. ↑ http://www.lab.anhb.uwa.edu.au/mb140/CorePages/Oral/oral.htm#LABSALIVA
  2. ↑ http://www.lab.anhb.uwa.edu.au/mb140/CorePages/Epithelia/Epithel.htm
  3. ↑ Thompson, Lester D. R. (2006). Head and Neck Pathology: A Volume in Foundations in Diagnostic Pathology Series (1st ed.). Churchill Livingstone. pp. 295-319. ISBN 978-0443069604.
  4. ↑ Thompson, Lester D. R. (2006). Head and Neck Pathology: A Volume in Foundations in Diagnostic Pathology Series (1st ed.). Churchill Livingstone. pp. 325-357. ISBN 978-0443069604.
  5. ↑ URL: http://emedicine.medscape.com/article/882358-overviewhttp://emedicine.medscape.com/article/882358-overview. Accessed on: 10 January 2011.
  6. ↑ 6.0 6.1 Thompson, Lester D. R. (2006). Head and Neck Pathology: A Volume in Foundations in Diagnostic Pathology Series (1st ed.). Churchill Livingstone. pp. 295. ISBN 978-0443069604.
  7. ↑ URL: http://moon.ouhsc.edu/kfung/jty1/opaq/PathQuiz/D2A001-PQ01-M.htm. Accessed on: 19 October 2010.
  8. ↑ Chest. May 1957. Vol. 31. No. 5. PP. 493-511. http://www.chestjournal.org/content/31/5/493.abstract
  9. ↑ Sequeiros-Santiago, G.; García-Carracedo, D.; Fresno, MF.; Suarez, C.; Rodrigo, JP.; Gonzalez, MV. (May 2009). "Oncogene amplification pattern in adenoid cystic carcinoma of the salivary glands.". Oncol Rep 21 (5): 1215-22. PMID 19360297.
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