Basal Cell Adenoma of the Salivary Glands: Understanding Your Pathology Report

Basal cell adenoma is a benign (non-cancerous) tumour of the salivary gland. It is made up of small cells that look similar to normal basal cells, which are found at the base of the glands in the salivary system. Although basal cell adenoma is rare, it is most commonly found in the parotid gland, the largest salivary gland located in front of the ear. It can also develop in the submandibular gland, sublingual gland, or in the minor salivary glands scattered throughout the mouth and throat.

Because basal cell adenoma is benign, it does not spread to other parts of the body. However, it can grow slowly over time and may cause symptoms depending on its size and location.

What causes basal cell adenoma?

Most basal cell adenomas develop sporadically, which means they arise without a known cause or risk factor. However, people with a rare inherited condition called familial cylindromatosis or Brooke-Spiegler syndrome may be more likely to develop basal cell adenomas. In these cases, the tumours may be multiple or occur alongside other types of skin or glandular tumours.

What are the symptoms of basal cell adenoma?

Many basal cell adenomas are painless and slow-growing, and they may not cause symptoms in the early stages. As the tumour grows, it may cause:

• A painless lump or mass in the cheek, jawline, or floor of the mouth (depending on the gland involved).

• Swelling in the area of the parotid or other salivary glands.

• Facial asymmetry due to the visible or palpable lump.

• Discomfort or pressure if the tumour presses on nearby nerves or structures.

• Difficulty swallowing or a feeling of fullness in the mouth or throat if the tumour arises from the minor salivary glands.

Although rare, very large tumours may cause facial nerve weakness or changes in facial movement.

How is this diagnosis made?

The diagnosis of basal cell adenoma is usually made after tissue is removed and examined under the microscope by a pathologist.

This may happen in one of two ways:

• A core needle biopsy or fine needle aspiration (FNA) may be performed to remove a small sample of tissue for initial diagnosis.

• The diagnosis can also be confirmed after surgical removal (excision or resection) of the entire tumour.

Pathologists use the microscopic appearance of the tumour, along with special stains or immunohistochemistry in some cases, to confirm the diagnosis.

What does basal cell adenoma look like under the microscope?

When examined under the microscope, basal cell adenoma is made up of small, darkly staining tumour cells that resemble basal cells of normal salivary glands. These cells often have a large, round nucleus that takes up most of the cell’s space, giving the tumour a dark blue appearance on routine stains.

The tumour cells are typically arranged in nests, cords, or tubules, and they may be separated by a bright pink material that looks like basement membrane, a layer normally found at the base of glands. This material may surround groups of tumour cells or appear as droplets within the tumour.

Basal cell adenomas are usually described as well-circumscribed and often encapsulated, meaning they have a clear border that separates the tumour from the surrounding normal salivary gland tissue. This helps distinguish basal cell adenoma from other salivary gland tumours, including malignant (cancerous) ones.

What is the treatment for basal cell adenoma?

The most common treatment for basal cell adenoma is surgical removal. Because these tumours are benign, surgery is usually curative, and no further treatment is required if the tumour is completely removed. In most cases, long-term follow-up is not necessary, although your doctor may recommend periodic monitoring if there is any concern about recurrence, especially if the tumour was not entirely removed.

What is the prognosis?

The prognosis for basal cell adenoma is excellent. Most people make a full recovery after surgery, and the risk of recurrence is very low. The tumour does not spread to lymph nodes or distant sites. If a tumour does recur, it is usually because some tumour cells were left behind during surgery, and another procedure may be needed.

Questions to ask your doctor

• Was the entire tumour removed?

• Did the tumour arise in a major or minor salivary gland?

• Do I need any follow-up or imaging after surgery?

• Is there any reason to suspect a genetic condition like familial cylindromatosis?