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.
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 | 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.
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.
Elsewhere in DurgiPedia
Connections
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 (StatPearls (NCBI Bookshelf), 2025); Salivary Gland Disorders (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.