Pleomorphic Adenoma: Symptoms, Causes, Treatment

What are the symptoms of pleomorphic adenoma?

Pleomorphic adenoma is a common, benign tumor that primarily affects the salivary glands, most often the parotid gland. While it is non-cancerous, it can still cause symptoms depending on its size, location, and growth rate. Here are the main symptoms associated with pleomorphic adenoma:

1. Painless Lump or Swelling

A slow-growing, firm, and painless lump is the most common symptom.
The lump usually develops near the jawline, under the ear, or in the mouth.
It may become more noticeable over time as it enlarges.

2. Facial Asymmetry

As the tumor grows, it may cause visible changes in facial structure or swelling on one side of the face.
This can be especially prominent when the tumor affects the parotid gland.

3. Difficulty Moving Facial Muscles

In rare cases, particularly if the tumor compresses facial nerves, there may be weakness or numbness in the face.
In more severe cases, this can result in facial paralysis.

4. Difficulty Swallowing (Dysphagia)

If the tumor grows within or near the oral cavity, it may obstruct swallowing, making it uncomfortable or painful to eat.

5. Hoarseness or Voice Changes

Tumors near the vocal cords or throat can sometimes cause changes in the voice or hoarseness.

6. Pain or Discomfort

Although pleomorphic adenomas are typically painless, some patients may experience pain if the tumor presses on nearby nerves or tissues.

7. Jaw Pain or Ear Pain

Occasionally, the tumor may cause discomfort in the jaw or around the ear, particularly as it enlarges.

8. Ulceration or Bleeding (in Rare Cases)

If the tumor becomes very large or grows into the oral cavity, it may ulcerate, leading to bleeding or infection, though this is rare.

9. Difficulty Opening the Mouth (Trismus)

If the tumor affects the muscles involved in jaw movement, it can cause trismus, or difficulty opening the mouth fully.

Summary of Symptoms:

Painless lump in the jaw, mouth, or near the ear.
Facial asymmetry due to swelling.
Facial weakness or numbness (rare).
Difficulty swallowing or changes in speech.
Pain or discomfort in the jaw or ear (uncommon).
Difficulty opening the mouth in advanced cases.

Although pleomorphic adenomas are benign, they can continue to grow and may recur after removal if not fully excised. In very rare cases, they can become malignant (transform into cancer), which is why prompt diagnosis and treatment are important.

What are the causes of pleomorphic adenoma?

The exact cause of pleomorphic adenoma is not fully understood, but several factors are thought to contribute to its development. Here are the key factors that may be involved:

1. Genetic Mutations

Certain genetic mutations are believed to play a role in the development of pleomorphic adenoma. For example:
- PLAG1 and HMGA2 gene rearrangements have been found in some cases, which may drive abnormal cell growth.
These mutations can lead to uncontrolled proliferation of epithelial and myoepithelial cells within the salivary glands, resulting in tumor formation.

2. Radiation Exposure

Exposure to radiation, particularly to the head and neck area, has been linked to an increased risk of salivary gland tumors, including pleomorphic adenomas.
Individuals who have undergone radiation therapy for other cancers may have a slightly higher risk of developing these tumors later in life.

3. Hormonal Influence

Some studies suggest that hormonal factors may play a role in pleomorphic adenoma, as the tumor is more commonly diagnosed in women, particularly between the ages of 30 and 60.
However, the exact hormonal mechanisms are not fully understood.

4. Environmental Factors

Exposure to certain environmental factors, such as chemicals or toxins, may contribute to the development of pleomorphic adenoma, although this link is not well-established.
There is limited evidence suggesting that occupational exposure to certain substances (like wood dust or industrial chemicals) may increase the risk of salivary gland tumors.

5. Inflammation or Injury

Chronic inflammation or trauma to the salivary glands may trigger abnormal cell growth, which could lead to the formation of a pleomorphic adenoma.
Repeated infections, injury to the salivary glands, or blockage of the ducts could potentially increase the risk of tumor development.

6. Age and Gender

Age: Pleomorphic adenoma most commonly affects individuals between 30 and 60 years of age, although it can occur at any age.
Gender: Women are more frequently affected than men, which might indicate a possible hormonal influence, though the exact connection remains unclear.

7. Salivary Gland Abnormalities

Abnormalities in the development or structure of the salivary glands may also contribute to tumor formation. Pleomorphic adenomas arise from epithelial and myoepithelial cells, which are involved in the production of saliva.

Summary of Causes:

Genetic mutations (such as PLAG1 and HMGA2 rearrangements).
Radiation exposure, especially to the head and neck.
Possible hormonal influences (more common in women).
Potential exposure to environmental toxins.
Chronic inflammation or injury to the salivary glands.
Age (30-60 years) and female gender.

While the exact cause of pleomorphic adenoma is not always clear, a combination of genetic and environmental factors is likely involved in its development. Fortunately, most cases are benign and treatable with surgical removal.

How is the diagnosis of pleomorphic adenoma made?

The diagnosis of pleomorphic adenoma typically involves a combination of clinical evaluation, imaging tests, and biopsy to confirm the presence and characteristics of the tumor. Here are the key steps in the diagnostic process:

1. Physical Examination

The physician will begin by conducting a thorough physical exam, focusing on the area of the salivary glands, particularly the parotid gland, submandibular glands, or minor salivary glands in the mouth.
The doctor will check for a painless lump or swelling in these areas, which is a common sign of pleomorphic adenoma.
They may also assess for facial nerve involvement (facial weakness or numbness) and any difficulties with swallowing or mouth movement.

2. Imaging Studies

Ultrasound: This non-invasive test is often the first imaging study used to assess the size, shape, and location of the tumor. It can help distinguish between solid and cystic components of the mass.
Magnetic Resonance Imaging (MRI): MRI provides detailed images of soft tissues and is particularly useful for evaluating the extent of the tumor and its relationship to surrounding structures.
Computed Tomography (CT) Scan: A CT scan may be used to assess larger tumors or those located deep within the salivary glands. It can help determine whether the tumor has invaded nearby tissues or bones. These imaging studies are critical for assessing the size, location, and potential malignancy of the tumor, although they cannot confirm the exact type of tumor.

3. Fine-Needle Aspiration Biopsy (FNA)

Fine-Needle Aspiration (FNA) is the most commonly used diagnostic technique to obtain a sample of the tumor.
During FNA, a thin needle is inserted into the tumor to withdraw a small amount of tissue or cells, which are then examined under a microscope by a pathologist.
FNA is minimally invasive and helps determine whether the tumor is benign (like pleomorphic adenoma) or malignant.

4. Core Needle Biopsy

In some cases, a core needle biopsy may be performed. This method uses a larger needle to remove a small core of tissue for more detailed analysis.
It is often used when more tissue is needed for an accurate diagnosis or when FNA results are inconclusive.

5. Histopathological Examination

The biopsy sample is examined by a pathologist, who looks for the characteristic features of pleomorphic adenoma under a microscope.
Pleomorphic adenomas are known for their mixed composition, with both epithelial (glandular) and mesenchymal (connective tissue) elements, often appearing as a mix of solid and cystic structures.

6. Other Diagnostic Tools

In rare cases where more detailed evaluation is needed, the doctor may recommend sialography (imaging of the salivary ducts using contrast dye) or positron emission tomography (PET) scans, especially if malignancy is suspected.

Summary of Diagnostic Steps:

Physical examination to assess for a lump or swelling.
Imaging studies (Ultrasound, MRI, or CT) to visualize the tumor.
Fine-needle aspiration biopsy (FNA) to analyze the cells.
Core needle biopsy if more tissue is needed.
Histopathological examination of the biopsy sample to confirm the diagnosis.

Accurate diagnosis is crucial because, while pleomorphic adenomas are typically benign, they can become malignant if not properly treated.

What is the treatment for pleomorphic adenoma?

The primary treatment for pleomorphic adenoma is surgical removal, as this tumor is benign but can grow over time and has a small risk of becoming malignant. Here’s a detailed overview of the treatment options:

1. Surgical Removal

Superficial Parotidectomy: For pleomorphic adenomas located in the parotid gland (the most common site), the standard procedure is a superficial parotidectomy. This involves removing the tumor along with the superficial portion of the gland while preserving the facial nerve.
Total Parotidectomy: If the tumor is located deep within the parotid gland or near the facial nerve, a total parotidectomy may be necessary. In this procedure, the entire gland is removed, with extra care taken to protect the facial nerve.
Submandibular or Minor Salivary Gland Surgery: For tumors in the submandibular gland or minor salivary glands (e.g., palate or lips), surgical excision of the affected gland or tissue is performed.
Wide Excision: For tumors located in other areas, such as the oral cavity or hard palate, wide excision with a margin of healthy tissue is performed to reduce the risk of recurrence.

2. Facial Nerve Consideration

Since pleomorphic adenomas in the parotid gland are often located near the facial nerve, careful surgical planning is necessary to avoid nerve damage. Surgeons use techniques to preserve the nerve, but in rare cases where the tumor is closely adherent to it, part of the nerve may need to be sacrificed, potentially causing temporary or permanent facial weakness.

3. Post-Surgery Monitoring

After surgery, patients are monitored for any signs of tumor recurrence. Even though pleomorphic adenomas are benign, they can recur, especially if the tumor was not completely removed or if the capsule of the tumor was violated during surgery.
Regular follow-up visits and imaging may be recommended to ensure there is no regrowth.

4. Radiation Therapy (in Rare Cases)

Radiation therapy is generally not used for pleomorphic adenoma since it is benign and surgery is highly effective.
However, radiation may be considered in cases where the tumor is inoperable, has recurred multiple times, or if it has transformed into a malignant tumor (carcinoma ex pleomorphic adenoma).

5. Reconstructive Surgery

In some cases, after the removal of a large tumor, especially from the salivary glands, reconstructive surgery may be needed to restore the appearance and function of the affected area.
This is particularly true if the surgery involved significant tissue removal, nerve involvement, or in cases of facial asymmetry after the procedure.

6. Management of Recurrence

Pleomorphic adenomas have a small risk of recurrence, particularly if the tumor is not completely excised during surgery. Recurrence can occur years or even decades after the initial surgery.
If the tumor recurs, further surgery is often required. Multiple recurrences may increase the risk of the tumor becoming malignant, so close follow-up is important.

Summary of Treatment:

Surgical removal (superficial or total parotidectomy, excision of submandibular or minor salivary glands).
Careful attention to preserving the facial nerve during surgery.
Radiation therapy may be considered in rare, recurrent, or inoperable cases.
Reconstructive surgery for functional or cosmetic reasons after tumor removal.
Regular monitoring to detect and manage any recurrence.

Surgery is the most effective treatment for pleomorphic adenoma, and with successful removal, the prognosis is generally excellent. However, long-term follow-up is key to ensuring the tumor does not recur.