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# Pleomorphic adenoma and Warthin tumour

- Lesion

Pleomorphic adenoma is a mixed tumour with cartilage-like stroma that recurs if shelled out; Warthin tumour is a cystic, lymphoid tumour of older smokers.

Updated Nov 12, 2026

## Key points

- Pleomorphic adenoma: about 60% of parotid tumours; painless, slow-growing, mobile mass; PLAG1 rearrangement or HMGA2 change.
- Morphologic heterogeneity, not nuclear pleomorphism: ducts and myoepithelial cells in myxoid, hyaline or chondroid stroma.
- Tongue-like protrusions through the capsule: recurrence after enucleation; superficial parotidectomy lowers it.
- Carcinoma ex pleomorphic adenoma: risk rises with years of presence; aggressive.
- Warthin tumour (papillary cystadenoma lymphomatosum): parotid only; men, older adults; strong link to smoking; bilateral or multifocal in a minority.
- Warthin histology: cysts lined by a double layer of oncocytic cells over dense lymphoid stroma with germinal centres.

On this page

- The basics Key points
- What it is
- Structure
- Step by step
- Pleomorphic adenoma vs Warthin tumour
- Markers
- Memory aid
- Elsewhere in DurgiPedia

- Clinical Clinical notes

- Study Test yourself

- Connections Connections

## What it is

Pleomorphic adenoma is the commonest salivary tumour, a benign mixed tumour of ductal, myoepithelial and mesenchymal-looking elements. Its incomplete capsule explains recurrence after simple enucleation, and long-standing tumours can become carcinoma. Warthin tumour is the second commonest benign tumour, found almost only in the parotid of older men who smoke, and may be bilateral or multifocal.

## Structure

- Pleomorphic adenoma gross: rounded, well-demarcated, usually under 6 cm; grey-white cut surface with bluish translucent chondroid areas.
- Microscopy: epithelial ducts and myoepithelial cells in sheets and strands within a chondromyxoid matrix; squamous metaplasia possible.
- Warthin gross: encapsulated round mass of a few centimetres, cysts and clefts with mucoid or brown fluid.
- Warthin microscopy: papillary folds of a bilayered oncocytic epithelium (inner columnar, outer cuboidal) on lymphoid tissue.

## Step by step

- In pleomorphic adenoma a reserve (stem-like) ductal or myoepithelial cell with a PLAG1 or HMGA2 change proliferates.
- Myoepithelial cells make the myxoid and chondroid matrix, so all elements come from one clone.
- The tumour pushes out through gaps in its thin capsule; islands left behind regrow.
- Warthin tumour may arise from salivary ductal inclusions inside intra- or periparotid lymph nodes; smoking promotes the oncocytic change.
- Lymphoid stroma in Warthin tumour is reactive, recruited by the epithelium.

## Pleomorphic adenoma vs Warthin tumour

| Feature | Pleomorphic adenoma | Warthin tumour |
| --- | --- | --- |
| [Frequency](https://durgical.com/en/conditions/parotid-gland-tumours/) | Commonest salivary tumour | Second commonest benign |
| Who | Middle-aged adults, women slightly more | Older men, smokers |
| Sites | Parotid, submandibular, minor glands | Parotid only |
| Histology | Epithelium, myoepithelium, chondromyxoid stroma | Oncocytic bilayer over lymphoid stroma |
| Recurrence | After enucleation | Rare |
| Malignant change | Carcinoma ex pleomorphic adenoma | Very rare |

## Markers

- PLAG1
- HMGA2

## Clinical notes

- Both present as painless parotid masses; facial nerve palsy points to malignancy instead.
- Pleomorphic adenoma recurs in a quarter of cases after enucleation but rarely after parotidectomy.
- Warthin tumours take up technetium on scintigraphy; malignant change is very rare.

## Memory aid

Warthin: the Smoker's parotid with lymph nodes inside; pleomorphic: many looks, one clone, keep the capsule.

## Test yourself

Think of the answer, then tap the question to see it.

## Why does pleomorphic adenoma recur after simple enucleation?

Its capsule is incomplete and tongue-like projections of tumour extend beyond it, leaving tumour behind.

## What does the term pleomorphic refer to in pleomorphic adenoma?

The variety of tissue elements (epithelial, myoepithelial and chondromyxoid stroma), not nuclear pleomorphism.

## What is the strongest risk factor for Warthin tumour?

Cigarette smoking.

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## Elsewhere in DurgiPedia

- [Salivary glands: serous and mucous acini](https://durgical.com/en/histology/salivary-glands-serous-and-mucous-acini/)

## Connections

## Related 4

- [Tobacco: how smoking injures tissue](https://durgical.com/en/general-pathology/tobacco-how-smoking-injures-tissue/)
- [Salivary gland tumours](https://durgical.com/en/general-pathology/salivary-gland-tumours/)
- [Sialadenitis and xerostomia](https://durgical.com/en/general-pathology/sialadenitis-and-xerostomia/)
- [Neck cysts and paraganglioma](https://durgical.com/en/general-pathology/neck-cysts-and-paraganglioma/)

## Related conditions 1

- [Parotid gland tumours](https://durgical.com/en/conditions/parotid-gland-tumours/)

[← All of general pathology](https://durgical.com/en/general-pathology/)

Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Parotid Cancer](https://www.ncbi.nlm.nih.gov/books/NBK538340/) (StatPearls (NCBI Bookshelf), 2025); [Salivary Gland Disorders](https://medlineplus.gov/salivaryglanddisorders.html) (MedlinePlus, US National Library of Medicine, 2025).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/general-pathology/pleomorphic-adenoma-and-warthin-tumour/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/pleomorphic-adenoma-and-warthin-tumour/