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

• Malignant Myoepithelioma of Salivary Gland
• Salivary Gland Myoepithelial Carcinoma

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

• Myoepithelial Carcinoma of Salivary Gland is a malignant epithelial tumor, composed almost only of myoepithelial cell type, affecting either the major or minor salivary glands. Myoepithelial carcinomas are described as the malignant version of benign myoepitheliomas
• The cause of formation of this salivary gland malignancy is generally unknown, but may be due to genetic factors. The tumor is observed in a wide age category of children and adults
• The signs and symptoms of Myoepithelial Carcinoma of Salivary Gland may include a tumor growth forming a lump, associated with pain in some cases, facial paralysis, and eating/chewing difficulties. The tumors exhibit severe local destruction in many cases
• The treatment for Myoepithelial Carcinoma of Salivary Gland involves a combination of surgery, chemotherapy, and radiation therapy, in most cases. The prognosis of the individual depends upon a set of several factors including the tumor stage and overall health of the individual

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

• Myoepithelial Carcinoma of Salivary Gland has been recorded in both children and adults
• The age range of presentation is between 14-86 years (average age 55 years)
• Both male and female genders are equally affected
• It is estimated that about 2% of salivary gland malignancies are myoepithelial carcinomas

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

The following risk factors may be specifically noted for Myoepithelial Carcinoma of Salivary Gland (observed in about 50% of the cases):

• Presence of the precursor lesion ‘benign myoepithelioma’, especially following its recurrence
• Presence of a pleomorphic adenoma

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 Myoepithelial Carcinoma of Salivary Gland? (Etiology)

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

• Studies on some tumors indicate chromosomal abnormalities involving chromosome 8
• Loss of chromosome material (non-specific loss) has also been observed in a few tumors

It is researched that a Salivary Gland Myoepithelial Carcinoma may arise sporadically (de novo), or from a preexisting tumor such as a benign myoepithelial tumor or a pleomorphic adenoma. However, the signs and symptoms and the course of the malignancy (in both cases) are the same.

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 Myoepithelial Carcinoma of Salivary Gland?

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

• Most tumors are slow-growing and present no pain initially, in many cases
• However, they are known to be locally infiltrative and destroy the surrounding tissue structures
• The tumors are generally single, nodular mass with infiltrative borders; they may be well-defined
• The size of the tumor can vary from 2 to 10 cm; some grow to large sizes
• Presence of visible swelling that is slowly increasing in size, typically on the side of the face, if the parotid gland is involved
• Tumors in the oral mucosa may ulcerate and bleed
• Pain while eating/chewing
• Neurological signs and symptoms, such as facial muscle weakness and pain, due to facial nerve involvement are usually noted
• The malignancies are known to erode the bone and present pain
• The tumor may spread to the lymph nodes (vascular invasion is often observed)
• 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: About 75% of the cases involve the parotid glands; the submandibular glands are also known to be affected
• Minor salivary glands: Some cases are observed in the oral mucosa (inside the mouth)

How is Myoepithelial Carcinoma of Salivary Gland Diagnosed?

A diagnosis of Myoepithelial 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

Note: The infiltrative and destructive nature of a malignant myoepithelioma, helps it to be differentiated from a benign myoepithelioma, which is necessary for a definite diagnosis of the 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 Myoepithelial Carcinoma of Salivary Gland?

Complications of Myoepithelial 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 is often observed
• Bones may be affected and undergo demineralization
• Tumor metastasis to local and distant sites is known to take place after a long duration
• 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 Myoepithelial Carcinoma of Salivary Gland Treated?

A combination of surgery, chemotherapy, and radiation therapy are used to treat Myoepithelial Carcinoma of Salivary Gland. The treatment may also depend upon the stage, overall health, age, and grade of the tumor.

The treatment measures 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 Myoepithelial Carcinoma of Salivary Gland be Prevented?

• Current medical research has not established a method of preventing the formation of Myoepithelial 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 Myoepithelial Carcinoma of Salivary Gland? (Outcomes/Resolutions)

• The prognosis of Myoepithelial Carcinoma of Salivary Gland may be assessed on a case-by-case basis. However, it is a locally-destructive tumor that can be very aggressive
• It has been reported that over 30% of the individuals perish due to the cancer, while 33% are cancer-free after appropriate treatment
• Single or multiple recurrences have been observed in the remaining 30% of the cases, necessitating further tumor management
• A negative outcome (poorer prognosis) is indicated by factors such as:
  • Cellular pleomorphism, observed to a high extent
  • Rapid and aggressive tumor spread
• 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 resectability 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 Myoepithelial 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/