Salivary glands

Primary salivary gland neoplasms

Benign

Canalicular adenoma


Editorial Board Member: Lisa Rooper, M.D.
Deputy Editor-in-Chief: Kelly Magliocca, D.D.S., M.P.H.
Adriana Handra-Luca, M.D., Ph.D.

Topic Completed: 25 October 2021

Minor changes: 25 October 2021

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PubMed Search: Canalicular adenoma salivary

Adriana Handra-Luca, M.D., Ph.D.
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Cite this page: Handra-Luca A. Canalicular adenoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/salivaryglandscanalicularadenoma.html. Accessed December 3rd, 2021.
Definition / general
Essential features
  • Monotonous, benign epithelial neoplasm; no basal / myoepithelial layer
  • Most frequently located in the minor salivary glands
  • May be multifocal
  • Treatment by surgical resection
Terminology
  • Retired terminology: canalicular tumor; canalicular mixed tumor; monomorphic adenoma, canalicular type; cystic adenoma; adenomatosis of accessory salivary glands
ICD coding
  • ICD-O: 8149/0 - canalicular adenoma
Epidemiology
Sites
  • Upper lip (80%), followed by buccal mucosa, lower lip, hard and soft palate (Head Neck Pathol 2015;9:181)
  • Extremely rare in major salivary glands (parotid); consider HMGA2-WIF1 fusion pleomorphic adenoma in differential diagnosis
Pathophysiology
Etiology
  • Unknown
Clinical features
Diagnosis
  • Clinical examination: movable, well circumscribed nodule (0.5 - 2 cm); unique or multiple nodules; possibly bilateral; exophytic mass or swelling; bluish or ulcerated mucosa (J Craniomaxillofac Surg 2017;45:1754)
  • Clinical differential diagnosis: mucocele, thrombosed vessel, lipoma, salivary gland tumor (Head Neck Pathol 2015;9:181)
Laboratory
  • Lack of specific laboratory tests
Radiology description
Radiology images

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Ultrasound examination image

Ultrasound examination (1B) and MRI (1C)

Prognostic factors
  • Favorable prognosis: complete resection
  • Persistence due to multifocality may be indistinguishable from recurrence (Head Neck Pathol 2015;9:181)
  • Recurrence rates: 3% recurrence, 5% recurrence after surgery
Case reports
Treatment
Clinical images

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Oral nodule Oral nodule

Oral nodule

Oral swelling / tumefaction / lesion

Oral swelling / tumefaction / lesion

Oral lesion after resection, postresection zone

Oral lesion after resection, postresection zone

Oral nodule

Oral nodule

Nodules (lip)

Nodules (lip)


Oral nodules / lesions

Oral nodules / lesions

Gross description
  • Often encapsulated; may be multifocal
  • Tumor may be resected as 1 or fragmented specimens
  • On cut surface: homogeneous or cystic spaces
  • Reference: Head Neck Pathol 2015;9:181
Gross images

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2 resected nodules

2 resected nodules

Resected specimen

Resected specimen

Resected specimen / nodule

Resected specimen / nodule

Resected lesion

Resected lesion

Resected nodule

Resected nodule

Frozen section description
Microscopic (histologic) description
  • Tumors may be single or multifocal
  • Bilayered strands or ribbons or anastomosing cords or branching tubules
  • Canalicular to cystic spaces between the cell strands; trabecular features
  • Lack of an outer layer of myoepithelial cells
  • Beading pattern, club ended cords
  • May infiltrate capsule and show extracapsular tumor islands (including in the normal salivary gland / multiple tumors)
  • Often cystic change
  • Tumoral columnar or cuboidal cells, foci of basaloid cells
  • Amphophil to eosinophilic cytoplasm, apocrine / oncocytic
  • Round to elliptical, uniform nuclei, focally nucleoli, basophilic chromatin, rare to absent mitoses
  • Mucous / mucinous metaplasia (Head Neck Pathol 2015;9:181)
  • Pigmented cells
  • Lacks or has exceptional necrosis (Head Neck Pathol 2015;9:181)
  • Microliths, tyrosine crystals, morules and squamous balls (intraluminal) (J Craniomaxillofac Surg 2017;45:1754, Head Neck Pathol 2015;9:181, Histopathology 1999;35:502)
  • Well vascularized, loose stroma; possibly sclerotic; perivascular eosinophil cuffs
  • Luminal or stromal histiocytes (foamy, lipofuscin, hemosiderin), luminal hemorrhage, degenerated / infarcted stroma (Head Neck Pathol 2015;9:181)
  • Malignant transformation not reported; lack of atypical figures (Head Neck Pathol 2015;9:181)
  • Occasionally reported as collision tumors or hybrid tumors (Eur J Cancer B Oral Oncol 1996;32B:251)
Microscopic (histologic) images

Contributed by Adriana Handra-Luca, M.D., Ph.D. (slides courtesy of Emmanuelle Vaz, M.D.)
Cystic tumor zone Cystic tumor zone

Cystic tumor zone

Solid tumor zone

Solid tumor zone

Microscopy

Microscopy

Canalicular pattern

Canalicular pattern


Alcian blue stain

Alcian blue stain

BCL2 expression

BCL2 expression

Virtual slides

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Canalicular adenoma

Cytology description
  • FNA smears (hematoxylin, eosin and May-Grünwald-Giemsa stains) pseudopapillary clusters, oval, spindle basaloid cells, scant cytoplasm or eosinophilic, isolated cells, bland nuclear chromatin, no visible nucleoli, no chondroid or myxoid substance (Head Neck Oncol 2014;6:32)
Cytology images

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Cytology of parotid case

Cytology of parotid case

Slides with cytology material

Slides with cytology material

Positive stains
Electron microscopy description
  • 2 rows of cells (tall columnar cells surrounding the canalicular lumina and conical cells situated between columnar cells, with direct contact with stromal connective tissue); interdigitating cells
  • Canalicular lumen: minimum amount of cell debris; no mucoid material
  • Small number of desmosomes
  • Ovoid nuclei, moderately prominent nucleoli, patchy condensation of chromatin
  • Reference: Cancer 1980;46:552
Electron microscopy images

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Apical zone of columnar cells

Apical zone of columnar cells

Basal zone of canalicular cells

Basal zone of canalicular cells

Zone of 2 parallel rows of tumor cells

Zone of 2 parallel rows of tumor cells

Basal zone of tumor cells

Basal zone of tumor cells

Molecular / cytogenetics description
Sample pathology report
  • Minor salivary gland, nodule resection:
    • Canalicular adenoma (1.5 cm); excised
Differential diagnosis
Board review style question #1
Which of the following is true about salivary gland canalicular adenoma?

  1. Cannot be multifocal
  2. Is a benign tumor
  3. Is rare in minor salivary glands
  4. Lacks stromal tissue
Board review style answer #1
B. Is a benign tumor

Comment Here

Reference: Canalicular adenoma
Board review style question #2
Which of the following is true about salivary gland canalicular adenoma?

  1. Is a type of adenocarcinoma
  2. Is often associated with lymph node metastases
  3. May contain squamous balls
  4. May show vascular emboli
Board review style answer #2
C. May contain squamous balls

Comment Here

Reference: Canalicular adenoma
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