Warthin tumour

by Jason Wasserman MD PhD FRCPC
July 6, 2025

Warthin tumour is a noncancerous tumour that most often develops in the parotid gland, the largest salivary gland located near the jaw and in front of the ear. It is the second most common type of salivary gland tumour, after pleomorphic adenoma.

Warthin tumour is sometimes referred to by older terms, such as papillary cystadenoma lymphomatosum or adenolymphoma, but these names are no longer recommended.

Is Warthin tumour a type of cancer?

No. Warthin tumour is not a cancer. It is a benign tumour, meaning it does not spread to other parts of the body or invade surrounding tissues. However, it may grow slowly over time, and in rare cases, it may be associated with other tumours in the salivary gland. Surgical removal is usually curative.

Where does Warthin tumour occur?

Warthin tumour almost always arises in the parotid gland, especially in the lower (tail) part of the gland. In some cases, it can also be found in lymph nodes near the parotid gland. Rarely, it may occur on both sides of the face (bilateral) or in more than one spot within the same gland (multifocal).

What are the symptoms of a Warthin tumour?

Most people notice a painless, slow-growing lump near the jaw, cheek, or neck. The lump is usually soft or rubbery. Other symptoms are uncommon but may include:

• Swelling or fullness in the area.

• Discomfort if the tumour becomes large.

• In rare cases, pain or facial nerve weakness, especially in a subtype called infarcted/metaplastic Warthin tumour.

Who gets Warthin tumour?

Warthin tumour most often affects older adults, with an average age of about 62 years. It occurs in both men and women, although historically it was much more common in men. Today, the gender difference is much smaller, particularly in Europe and North America.

It is rare in children and uncommon in Black African populations.

What causes a Warthin tumour?

The exact cause is not fully known, but cigarette smoking is the most well-established risk factor. People who smoke are more likely to develop Warthin tumours, and they are also more likely to have tumours on both sides of the face.

Other possible risk factors include:

• Radiation exposure (e.g., atomic bomb survivors).

• Autoimmune conditions, such as thyroiditis.

• Certain viral infections or immune system activity have been suggested, but these links are still being studied.

How is a Warthin tumour diagnosed?

Diagnosis usually involves a combination of imaging and biopsy:

• Imaging: Ultrasound, CT scan, or PET-CT may reveal a well-defined mass, often with cystic (fluid-filled) areas, and sometimes multiple tumours.

• Fine-needle aspiration (FNA): A small sample of cells is taken from the lump and examined under the microscope. The sample typically exhibits a mixture of oncocytic cells, lymphocytes, and background debris.

A definite diagnosis is usually confirmed after the tumour is surgically removed and examined in full by a pathologist.

What does a Warthin tumour look like under the microscope?

When examined under the microscope, the Warthin tumour has a distinctive appearance composed of two parts: epithelial cells and lymphoid tissue.

The epithelial cells line cystic (fluid-filled) spaces and form papillary (finger-like) structures. These cells form a two-layered (bilayered) lining, with tall column-shaped cells on the inside and smaller cuboidal cells on the outside. The epithelial cells are oncocytic, meaning they have a granular appearance under the microscope. The word granular refers to the presence of many small, grain-like structures in the cytoplasm (the area surrounding the nucleus), caused by an increased number of mitochondria.

The lymphoid stroma, or supporting tissue, resembles lymph node tissue and often contains germinal centres, which are small collections of immune cells.

In some cases, Warthin tumours may show metaplastic changes, where the typical oncocytic cells are replaced by squamous (skin-like) or mucinous (mucus-producing) cells. These changes are most often seen in tumours that have been previously biopsied or damaged (infarcted). Although these features can appear concerning, they are not a sign of cancer.

What other conditions can look like Warthin tumour?

The primary concern when diagnosing a metaplastic Warthin tumour is to ensure it is not a mucoepidermoid carcinoma, a type of salivary gland cancer. A special genetic test may be performed to detect a MAML2 gene rearrangement, which is characteristic of mucoepidermoid carcinoma but not of Warthin tumour.

Is molecular testing required to make this diagnosis?

In most cases, molecular testing is not needed to diagnose Warthin tumour. However, in difficult cases, a test to check for MAML2 gene changes may help distinguish it from mucoepidermoid carcinoma.

How is a Warthin tumour treated?

The usual treatment is surgical removal of the tumour. This is especially recommended if the tumour is:

• Causing symptoms.

• Increasing in size.

• Uncertain on imaging or biopsy.

Surgery is curative in nearly all cases. If a tumour comes back, it is usually because it was multifocal or not completely removed during the first surgery.

What is the prognosis for Warthin tumour?

The prognosis is excellent. Warthin tumour is not cancer and does not spread to other parts of the body. Once removed, it almost never recurs, and malignant transformation is extremely rare.

In very rare cases, a cancer can arise within a Warthin tumour, either from the epithelial (glandular) or lymphoid (immune cell) component. These cases are exceptionally uncommon.

Questions to ask your doctor

• Will I need surgery to remove it?

• Could the tumour come back?

• Do I need follow-up imaging or exams?

• What are the risks of surgery?

• Is there any chance this tumour could turn into cancer?