Salivary gland tumors are rare forms of cancer. There are different forms of salivary gland cancers, each with unique features. Polymorphous low grade adenocarcinoma is one of the types of salivary gland tumors.

Salivary gland tumors are rare cancers occurring in the mouth and throat area. Polymorphous low grade adenocarcinoma (PLGA) is one type of salivary gland cancer.

This article discusses polymorphous low grade adenocarcinoma, its causes, diagnosis, and treatment options.

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Salivary gland tumors are rare cancers that affect approximately 3 in 100,000 people per year, in most industrialized countries.

PLGA is a low grade malignant tumor that affects the minor salivary glands in the oral cavity. A 2019 study revealed that 55% of PLGA occurs in the hard palate of the oral cavity.

These tumor cells can originate from the salivary gland or arise as metastatic spread-tumor cells originating from a distant primary cancer site. Out of over 8,000 people with intraoral salivary gland tumors, PLGA accounted for 1.2%, according to researchers from the University of North Carolina.

Polymorphous low grade adenocarcinoma cells have lower rates of metastasis, but they can still metastasize. Medical authorities believe they can possibly transform to become highly metastatic.

Read more about salivary gland cancer.

Researchers do not yet know the specific cause of PLGA. However, exposure to factors, such as toxic chemicals that cause DNA mutation, will typically result in abnormal cell proliferation and growth. The following are some of the risk factors for salivary gland cancer, including PLGA:

  • Age: Adults above 55 years old are typically at risk of PLGA.
  • Radiation exposure: Radiotherapy to surrounding regions, such as the head or neck, may increase the risk of PLGA.
  • Exposure to radioactive substances: Individuals who experience exposure tosome radioactive substances are typically susceptible to PLGA.
  • Environmental toxins: Occupational or environmental exposure to toxic chemicals, such as pesticides, industrial solvents, or sawdust, could raise the risk of developing PLGA.

These risk factors are not the direct cause of PLGA, so a person may experience exposure to them and not develop a salivary gland tumor.

The symptoms of PLGA differ for each person and may develop without any physical growth in some people. The following are typical symptoms of salivary gland cancer, including PLGA:

  • painless swelling or a lump on the face, neck, or mouth
  • facial numbness
  • progressive facial weakness and muscle paralysis
  • pain or swelling in the face, jaw, or neck

Of note, these symptoms are not indicative of PLGA, as other medical conditions can also cause them.

Therefore, individuals with these symptoms typically require proper clinical evaluation to accurately diagnose and exclude salivary gland tumors, including PLGA.

Diagnosing PLGA is typically a combination of clinical evaluation and laboratory testing for confirmation.

During the clinical evaluation, a doctor typically takes a clinical history and examines any possible swelling in the oral cavity, face, or neck.

Thereafter, the following laboratory tests are critical for accurately diagnosing PLGA:

  • Biopsy: A biopsy involves removing tissue samples from the tumor and conducting a microscopic examination to study the cellular structure.
  • Immunohistochemistry: Immunohistochemistry is helpful in some people when diagnosis from microscopic examination of the biopsy is not clear.

PLGA may share similar cellular structures with other salivary gland tumors. Because of this, an immunohistochemical stain differentiates PLGA by identifying its specific markers. These cellular markers distinguish PLGA from other tumors.

Other supporting radio imaging tests, such as ultrasounds, MRI scans, or CT scans can help a doctor clearly visualize and identify the specific location and extent of the tumor.

There are different treatment options for polymorphous low grade adenocarcinoma, and the stage of the tumor at diagnosis could influence treatment choices.

The following are the standard treatment modalities for PLGA:

  • Surgical removal: This is the primary treatment method. It typically entails complete surgical excision of the tumor and the subjacent bone in some people.
  • Radiation therapy: Radiation therapy may be necessary for people when complete surgical resection is not possible or for people with malignant tumor cells with a high risk of recurrence.

PLGA has a chance of recurrence, so follow-up care is critical for early diagnosis and treatment. Depending on the size of the swelling, the PLGA cells could grow and compress surrounding tissues in the oral cavity or face.

Also, PLGA that locally invades nearby tissues may be difficult for doctors to surgically remove completely.

The future outlook and survival rates of PLGA depend on several factors, such as the stage of the tumor at diagnosis, its location, and its aggressiveness.

Generally, PLGA prognosis is good and has a 5-year survival rate of 75–100%, according to a 2019 study. Early diagnosis and prompt treatment are essential for a positive outlook for PLGA in most people.

Polymorphous low grade adenocarcinoma is a low grade malignant tumor that commonly affects the minor salivary glands in the oral cavity. The exact cause of PLGA is unknown, but exposure to toxic chemicals and radiotherapy could increase the risk of developing it.

Individuals with PLGA may present with a painless growth in the face or oral cavity, while some may not notice any symptoms.

Diagnosing PLGA typically involves clinical evaluation and laboratory testing, such as biopsy for microscopic examination and immunohistochemical staining.

Treatment of PLGA involves complete surgical removal of the tumor growth and radiotherapy.