Salivary glands

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. 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).
   • Most tumours in this gland are benign.
2. Submandibular:
   • Serous and mucinous glands.
3. Sublingual:
   • Mucinous glands.

Images:

• Salivary glands - normal (uwa.edu.au).
• Submandibular gland (ouhsc.edu) - from a Pathology Quiz.

Memory devices:

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

Overview

Benign tumours

Tabular form - adapted from Thompson

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

Malignant tumours

Tabular form - adapted from Thompson

	Architecture	Morphology	Cell borders	Cytoplasm	Nucleus	DDx	Other
Mucoepidermoid carcinoma	cystic & solid	epithelioid	distinct	fuffy, clear, abundant	nuclei sm.	?	?
Acinic cell adenocarcinoma (AcCC)	acinar (islands)	epithelioid	clear	granular, generous	stipled, +/-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

DDx by site

Palate:

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

Benign

Mucocele

• Mucous.

Pleomorphic adenoma

Epidemiology

Features:

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

Histology

Features:

• 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

• Basophilic cells.
• Nests.

Canalicular adenoma

• 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

• Benign counterpart of sebaceous carcinoma.

Oncocytoma

• 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.

Features:

• Abundant fluffy cytoplasm - with large mucin vacuole.
• Nucleus distorted by mucin vacuole.

Images:

• Mucoepidermoid carcinoma 2 (WC).
• Mucoepidermoid carcinoma 3 (WC).

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.
  • 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:

• 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

• Head and neck pathology.
• Thyroid gland.
• Breast.
• Head and neck cytopathology.