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Mucoepidermoid Carcinoma of Salivary Gland

Last updated Nov. 29, 2018

Approved by: Krish Tangella MD, MBA, FCAP

A Mucoepidermoid Carcinoma (MEC) of Salivary Gland is a type of malignant glandular epithelial tumor affecting either the major or minor salivary glands. It is observed in a wide age category of children and adults. MEC constitutes the most common primary tumor affecting the salivary glands.


What are the other Names for this Condition? (Also known as/Synonyms)

  • MEC of Salivary Gland
  • Mixed Epidermoid and Mucus Secreting Carcinoma of Salivary Gland
  • Salivary Gland Mucoepidermoid Carcinoma

What is Mucoepidermoid Carcinoma of Salivary Gland? (Definition/Background Information)

  • A Mucoepidermoid Carcinoma (MEC) of Salivary Gland is a type of malignant glandular epithelial tumor affecting either the major or minor salivary glands. It is observed in a wide age category of children and adults. MEC constitutes the most common primary tumor affecting the salivary glands
  • The cause of formation of this salivary gland malignancy is generally unknown, but may be due to genetic factors. No definitive risk factors are observed, though salivary gland cancers are known to be influenced by factors such as exposure to radiation sources and occupational exposure to hazardous chemicals/products
  • The signs and symptoms of Mucoepidermoid Carcinoma of Salivary Gland may include a tumor growth forming a lump, associated with pain in some cases, facial paralysis, and eating/chewing difficulties. Some tumors cause bleeding from the mouth and ear discharge
  • The treatment for Mucoepidermoid Carcinoma of Salivary Gland involves a combination of surgery, chemotherapy, and radiation therapy, in most cases. With prompt diagnosis and adequate treatment, the prognosis of MEC of Salivary Gland is generally good

Who gets Mucoepidermoid Carcinoma of Salivary Gland? (Age and Sex Distribution)

  • Mucoepidermoid Carcinoma of Salivary Gland has been recorded in both children and adults; in general, average age of presentation is 45 years and peak period between 20-40 years
  • It is reported to be uniformly distributed across age groups; although, younger children and much older adults are known to be less affected
  • Tumors that arise in the palate are seen at a slightly younger age; 60% of the cases are seen below age 40 years. Tumors that affect the tongue are seen in slightly older age (above mean age of 45 years)
  • Even though both genders are affected, a slight female predominance is noted; a 3:2 female-male ratio is noted. However, when the retromolar pad (at the back of the mouth) and tongue is affected, an even greater female predominance is noted
  • No ethnic or racial preference has been observed

What are the Risk Factors for Mucoepidermoid Carcinoma of Salivary Gland? (Predisposing Factors)

No risks are evident for Mucoepidermoid Carcinoma of Salivary Gland. Nevertheless, the following risk factors are generally noted for salivary gland cancers:

  • Exposure to ionizing radiation (which may be from natural or artificial sources)
  • Occupations involving woodwork, plumbing, and mining (asbestos)
  • Working in manufacturing industry related to certain materials, such as rubber products

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Mucoepidermoid Carcinoma of Salivary Gland? (Etiology)

The exact cause of Mucoepidermoid Carcinoma of Salivary Gland formation is unknown. It is suggested that genetic factors may have a role in their formation.

  • Many tumors show chromosomal translocation t(11;19)(q21;p13) as the only genetic abnormality
  • Rarely, studies indicate loss of genetic material involving chromosome 5, 8, 9, 12, or 16
  • Also, infrequently, mutations involving the H-ras gene have been recorded

In general, it is known that cancers form when normal, healthy cells begin transforming into abnormal cells - these cancer cells grow and divide uncontrollably (and lose their ability to die), resulting in the formation of a mass or a tumor.

  • The transformation of normally healthy cells into cancerous cells may be the result of genetic mutations. Mutations allow the cancer cells to grow and multiply uncontrollably to form new cancer cells
  • These tumors can invade nearby tissues and adjoining body organs, and even metastasize and spread to other regions of the body

What are the Signs and Symptoms of Mucoepidermoid Carcinoma of Salivary Gland?

Mucoepidermoid Carcinoma of Salivary Gland signs and symptoms may include the following:

  • The tumors are generally single, solid/firm or cyst-like
  • Most MEC tumors present no pain; although, even small-sized sublingual gland tumors show pain
  • Tumors involving the minor glands (inside the mouth) may present a bluish-red skin surface and appear like a small marble (or a mucocele)
  • Presence of visible swelling, typically on the side of the face, that is slowly increasing in size
  • Pain while eating/chewing, bleeding from the mouth
  • Neurological signs and symptoms, such as facial muscle weakness and pain, due to facial nerve involvement may be noted
  • Abnormal pricking or burning sensation that may be non-specific
  • Some malignancies are known to erode the bone and present severe pain
  • Discharge from the ear (otorrhea)
  • Initially, the overlying skin may not appear inflamed or present changes in texture or color
  • As the tumor progress and becomes larger in size, changes in the overlying skin including ulceration may be noted
  • Involvement of the parotid glands are seen in a majority of the cases
  • Persistent facial pain at the site of swelling of the tumor; this requires an immediate checkup by a healthcare provider

Location of the malignant tumor:

  • Major salivary glands: Over 50% of the cases involve the major glands. In 45% of the cases, the parotid glands are involved; while, 7% are seen in the submandibular glands, and 1% in the sublingual glands
  • Minor salivary glands: A little less than 50% of the cases are observed in the mouth, with the soft/hard palate and inner cheek lining (buccal mucosa), being the most common sites

How is Mucoepidermoid Carcinoma of Salivary Gland Diagnosed?

A diagnosis of Mucoepidermoid Carcinoma of Salivary Gland is made using the following tools:

  • Complete evaluation of family (medical) history, along with a thorough physical examination
  • Plain X-ray of the head and neck
  • Ultrasound scan of the affected salivary gland
  • CT or CAT scan with contrast of the head and neck may show a tumor mass. This radiological procedure creates detailed 3-dimensional images of structures inside the body
  • MRI scans of head and neck: Magnetic resonance imaging (MRI) uses a magnetic field to create high-quality pictures of certain parts of the body, such as tissues, muscles, nerves, and bones. These high-quality pictures may reveal the presence of the tumor

Although the above modalities can be used to make an initial diagnosis, a tissue biopsy of the tumor is necessary to make a definitive diagnosis to begin treatment. The tissue for diagnosis can be procured in multiple different ways which include:

  • Fine needle aspiration (FNA) biopsy of the tumor: A FNA biopsy may not be helpful, because one may not be able to visualize the different morphological areas of the tumor. Hence, a FNA biopsy as a diagnostic tool has certain limitations, and an open surgical biopsy is preferred
  • Salivary gland core biopsy of the tumor
  • Salivary gland open biopsy of the tumor

Tissue biopsy of the tumor:

  • A tissue biopsy of the nodule is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis
  • Biopsy specimens are studied initially using Hematoxylin and Eosin staining. The pathologist then decides on additional studies depending on the clinical situation
  • Sometimes, the pathologist may perform special studies, which may include immunohistochemical stains, molecular testing, and very rarely, electron microscopic studies to assist in the diagnosis

A differential diagnosis may be necessary to eliminate tumors presenting similar signs and symptoms and for a definitive diagnosis of MEC:

  • Clear cell carcinoma
  • Squamous cell carcinoma
  • Adenosquamous carcinoma
  • Cystadenoma
  • Inverted ductal papilloma
  • Necrotizing sialometaplasia

Note: MEC tumors are classified as low-grade and high-grade tumors. A low-grade tumor is usually less-aggressive than a high-grade tumor.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Mucoepidermoid Carcinoma of Salivary Gland?

Complications of Mucoepidermoid Carcinoma of Salivary Gland may include:

  • Cosmetic concerns (facial disfigurement) and severe emotional stress
  • Ulceration and bleeding from the tumor
  • Large-sized tumors may compress adjoining tissues and structures resulting in additional complications
  • Breathing or swallowing difficulties (if tumor mass obstructs the food-pipe or wind-pipe)
  • Recurrence of the tumor after surgery
  • Bones may be affected and undergo demineralization
  • Tumor metastasis to local and distant sites:
    • Metastasis of parotid gland tumors take place to the adjacent lymph nodes, and then to the submandibular regions
    • Submandibular tumors are known to spread to the lymphatic system
    • Mouth or intraoral MEC tumors are known to metastasize to the submandibular glands, post-auricular and neck lymph nodes
    • Palate tumors may metastasize to the skull base and respiratory tract
    • Higher or advanced stage tumors can involve the brain, lung, liver, and bones
  • Surgical complications: Surgery to remove the tumor mass may result in facial nerve palsy and gustatory sweating (Frey syndrome)
  • Post-surgical wound infection
  • Side effects from chemotherapy (such as toxicity), radiation therapy

How is Mucoepidermoid Carcinoma of Salivary Gland Treated?

A combination of surgery, chemotherapy, and radiation therapy are used to treat Mucoepidermoid Carcinoma of Salivary Gland. The treatment may also depend upon the stage, overall health, age, and grade of the tumor. A universally acceptable tumor histological grading is currently unavailable.

The treatment measures for MEC of Salivary Gland may involve:

  • Wide surgical excision with removal of the entire lesion is the standard treatment mode
  • High-dose radiation therapy may be used after surgery, to destroy the remaining tumor cells
  • When the tumor is at an inaccessible location, or is unsafe for surgical intervention, non-invasive procedures, such as chemotherapy and radiation therapy (using fast neutron-beam), may be considered
  • Recurrent salivary gland tumors are also known to respond better to fast neutron-beam radiation therapy than other treatment modes
  • Embolization is used to provide temporary relief from the symptoms, and reduce blood loss during a surgical procedure
  • Clinical trial therapies (especially for stage IV disease) including therapeutic drugs, radiation, stem cell transplantation, and monoclonal antibodies, either singly or in combination of various therapies
  • Post-operative care is important: A minimum activity level is to be ensured until the surgical wound heals
  • Follow-up care with regular screening and check-ups are important, to watch for recurrence and any metastatic behavior

How can Mucoepidermoid Carcinoma of Salivary Gland be Prevented?

  • Current medical research has not established a method of preventing the formation of Mucoepidermoid Carcinoma of Salivary Gland
  • Regular medical screening at periodic intervals with blood tests, radiological scans, and physical examinations, are mandatory for those who have been diagnosed with the tumor
  • Due to its high metastasizing potential and chances of recurrence, often several years of active follow-up and vigilance is recommended

What is the Prognosis of Mucoepidermoid Carcinoma of Salivary Gland? (Outcomes/Resolutions)

  • The prognosis of Mucoepidermoid Carcinoma of Salivary Gland is generally better with early diagnosis and prompt treatment, rather than a late diagnosis and delayed treatment. The prognosis is typically better than other salivary gland malignancies
  • According to some studies, the death rate associated with high-grade MEC tumors affecting the major salivary glands is around 11%, while the same is around 5% for minor salivary gland MEC tumors
  • A negative outcome (poorer prognosis) is indicated by factors such as:
    • Advanced tumors with metastasis
    • Tumors that cannot be fully resected/removed
    • Treatment-associated complications
    • High-grade parotid gland and minor salivary gland tumors
  • The prognosis of salivary gland cancer, in general, depends upon a set of several factors that include:
    • Stage of tumor: With lower-stage tumors, when the tumor is confined to site of origin, the prognosis is usually excellent with appropriate therapy. In higher-stage tumors, such as tumors with metastasis, the prognosis is poor
    • The size of the tumor: Individuals with small-sized tumors fare better than those with large-sized tumors
    • Overall health of the individual: Individuals with overall excellent health have better prognosis compared with those with poor health
    • Age of the individual: Older individuals generally have poorer prognosis than younger individuals
    • Individuals with bulky disease have a poorer prognosis
    • Involvement of the lymph node can adversely affect the prognosis
    • Involvement of vital organs may complicate the condition
    • The surgical respectability of the tumor (meaning, if the tumor can be removed completely)
    • Whether the tumor is occurring for the first time, or is a recurrent tumor. Recurring tumors have worse prognosis compared to tumors that do not recur
    • Response to treatment of salivary gland cancer: Tumors that respond to treatment have better prognosis compared to tumors that do not respond to treatment
    • Progression of the condition makes the outcome worse

Additional and Relevant Useful Information for Mucoepidermoid Carcinoma of Salivary Gland:

There are 3 major types of salivary glands and these include the following:

  • Parotid glands, found on the sides of the face
  • Submandibular glands located at the back of mouth, on both sides of the jaw
  • Sublingual glands that are seen under the floor of the mouth

The following article link will help you understand other cancers and benign tumors:

http://www.dovemed.com/diseases-conditions/cancer/

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: April 27, 2017
Last updated: Nov. 29, 2018