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

• Lobular Carcinoma of Salivary Gland
• Salivary Gland Polymorphous Low-Grade Adenocarcinoma
• Terminal Duct Carcinoma of Salivary Gland

What is Polymorphous Low-Grade Adenocarcinoma of Salivary Gland? (Definition/Background Information)

• A Polymorphous Low-Grade Adenocarcinoma (PLGA) of Salivary Gland is a type of malignant epithelial tumor, commonly affecting the minor salivary glands. It constitutes over one-fourth of the malignancies affecting the minor salivary glands
• PLGA, as the name indicates, is a low-grade malignancy with some metastatic potential, but showing an infiltrative growth pattern. The tumor is mostly observed in middle-aged and older adults
• 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 Polymorphous Low-Grade Adenocarcinoma of Salivary Gland may include a tumor growth forming a lump, associated with pain in some cases, eating/chewing difficulties, and infiltration to the jawbone
• The treatment for Polymorphous Low-Grade Adenocarcinoma of Salivary Gland involves surgery. Other measures, such as chemotherapy and radiation therapy, may be considered on a case-by-case basis. With prompt diagnosis and adequate treatment, the prognosis of PLGA of Salivary Gland is generally excellent

Who gets Polymorphous Low-Grade Adenocarcinoma of Salivary Gland? (Age and Sex Distribution)

• Polymorphous Low-Grade Adenocarcinoma of Salivary Gland has been recorded in teens, young, middle-aged and elderly adults; age range 16-94 years (average age of diagnosis is 59 years)
• 7 in 10 tumors are observed in adults in the 6th and 7th decade. Young and old children are extremely rarely diagnosed with this malignancy
• Even though both genders are affected, a female predominance is noted (2:1 female-male ratio)
• No ethnic or racial preference has been observed
• PLGA of Salivary Gland is the second most common tumor observed in the minor (intraoral) salivary glands; over 25% of all malignant tumors at this site are PLGA tumors

What are the Risk Factors for Polymorphous Low-Grade Adenocarcinoma of Salivary Gland? (Predisposing Factors)

No risks are evident for Polymorphous Low-Grade Adenocarcinoma 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 Polymorphous Low-Grade Adenocarcinoma of Salivary Gland? (Etiology)

The exact cause of Polymorphous Low-Grade Adenocarcinoma of Salivary Gland formation is unknown. It is suggested that genetic factors may have a role in their formation. However, no specific genetic abnormality is seen. 

• A few study reports have revealed some of the following abnormalities:
  • Chromosomal studies have revealed anomalies involving the long-arm (q) and short-arm (p) of chromosome 12
  • Occasionally, abnormalities on chromosome 8 and clonal translocation t(6;9)(p21;p22) were noted
  • Monosomy 22 was observed on a solitary case
• 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 Polymorphous Low-Grade Adenocarcinoma of Salivary Gland?

Polymorphous Low-Grade Adenocarcinoma of Salivary Gland signs and symptoms may include the following:

• The tumor mass may grow at a slow rate in the mouth and may present no pain. The palate or roof of the mouth, is the most common site for PLGA
• The tumors are generally single and firm nodules with clearly-defined boundaries
• The mean size is over 2 cm, though some tumors may grow to large sizes
• Presence of dilated blood vessels in the form of spider veins (telangiectasia) may be noted
• Bleeding and skin ulceration is not common, but may be observed in some cases
• Neurological signs and symptoms, such as facial muscle weakness and pain, due to facial nerve involvement may be seen
• Pain while eating/chewing
• Persistent facial pain at the site of swelling of the tumor; this requires an immediate checkup by a healthcare provider
• Tumor infiltration into the bone and jaw

Some oral lesions have been present for several decades (up to 40 years reported); while others, for a few weeks, prior to presenting significant symptoms.

Location of the malignant tumor:

• Minor salivary glands: The tumors form predominantly within the mouth
  • 3 out of 5 tumors are observed in the palate
  • Other intraoral sites include the inner cheek lining (buccal mucosa), upper lip, back of the mouth (retromolar pad), and tongue
• Major salivary glands: Involvement of the major glands is only rarely observed
• Infrequent cases of tumors in the nasal cavity, tear glands, and nasopharynx (upper pharyngeal region at the nasal cavity) have been reported

How is Polymorphous Low-Grade Adenocarcinoma of Salivary Gland Diagnosed?

A diagnosis of Polymorphous Low-Grade Adenocarcinoma 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 PLGA:

• Pleomorphic adenoma
• Adenoid cystic carcinoma 

When the tumor cells are observed under the microscope by a pathologist, the following morphologic configurations may be noted:

• Lobular pattern
• Papillary or papillary-cystic pattern
• Cribriform pattern
• Trabecular pattern

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 Polymorphous Low-Grade Adenocarcinoma of Salivary Gland?

Complications of Polymorphous Low-Grade Adenocarcinoma 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: It is estimated that nearly 9-17% of the tumors recur locally following surgery to remove them
• Bones may be affected and undergo demineralization
• Rarely, tumor metastasis to local and distant sites:
  • Regional metastasis is very uncommon and may take place only after an extended period
  • Metastasis to the cervical lymph nodes (of the neck) has been observed in the case of some tumors, with papillary morphologic pattern
• 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 Polymorphous Low-Grade Adenocarcinoma of Salivary Gland Treated?

A combination of surgery, chemotherapy, and radiation therapy are used to treat Polymorphous Low-Grade Adenocarcinoma of Salivary Gland. The treatment may also depend upon the stage, overall health, age, and pattern/configuration of the tumor.

The treatment measures for PLGA of Salivary Gland may involve:

• Wide surgical excision with removal of the entire lesion is the treatment of choice. In case the cervical lymph nodes are affected, then a lymph node dissection may be undertaken
• 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 Polymorphous Low-Grade Adenocarcinoma of Salivary Gland be Prevented?

• Current medical research has not established a method of preventing the formation of Polymorphous Low-Grade Adenocarcinoma 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 metastasizing potential and chances of recurrence, often several years of active follow-up and vigilance is recommended

What is the Prognosis of Polymorphous Low-Grade Adenocarcinoma of Salivary Gland? (Outcomes/Resolutions)

• The prognosis of Polymorphous Low-Grade Adenocarcinoma of Salivary Gland is generally excellent with early diagnosis and prompt treatment
• The rate of metastasis observed is between 9-15%, and deaths due to Salivary Gland PLGA tumor is very infrequently observed. Also, metastasis to distant sites is very uncommon
• 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 Polymorphous Low-Grade Adenocarcinoma 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/