The second most common tumour of salivary glands; it is also benign. There are many other names for this tumour, most of them have -lymph- somewhere in the title and therefore Warthin tumour is used to separate this from the malignant -lymph- tumours (eg. lymphoma, lymphadenoma).
Epidemiology
Warthin tumour has a highly variable incidence based on geography. It is uncommon in the USA but more common in Europe. It occurs at an older age than the other salivary gland tumours. It is nearly always located in the parotid gland.
Aetiology and Pathogenesis
Smoking appears to be closely related to incidence of Warthin tumour; it was previously almost exclusively in men but the incidence has now equalised. The exact cell/s of origin is unclear; there is speculation that the unique location of lymph nodes within the substance of the parotid gland may be the reason for its predilection for the parotid gland.
Natural History
The tumour is usually slow growing and is non-invasive. Resection is usually curative. About 1% of cases have been reported to transform to a malignant tumour.
Clinical Presentation
Warthin tumour is usually a small mass (2 - 4 cm) and painless.
Tumour/Normal Tissue Features
Macroscopically the tumour consists of multiple spherical masses mixed with visible cystic areas. The solid portions are usually light coloured. There is always a capsule; this is better defined than pleomorphic adenoma.
The tumour has a classical microscopic appearance, with papillae extending into the cystic spaces. The lining of the cysts is bilayered epithelium; a superficial columnar layer with palisading, basally located nuclei; and a basal layer of cuboidal cells. The solid areas contain lymphoid tissue, usually with germinal centres. Occasionally the tumour may be partially destroyed by an inflammatory process.
Immunohistochemistry shows normal lymphocyte populations consistent with a reactive lymph node.
The classical Warthin tumour is perhaps the most easily recognisable tumour of the salivary glands.
