Submandibular Gland


Jul 31

The submandibular gland produces more saliva than the other glands; it sits just deep to the jaw at the midpoint between the chin and the angle of the jaw. Several important nerves are located in close proximity of the gland, including: (1) the marginal mandibular nerve that moves the lower lip (2) the hypoglossal nerve that moves half the tongue (3) the lingual nerve that is in change of taste and sensation of the tongue. The surgical anatomy of these neural structures is very complex but quite consistent in expert hands. There are also several lymph nodes around this gland that may be involved with tumors and will need to be removed at times.

Risk Factors

The most well known cause is exposure to radiation, either in the environment or as treatment for a cancer of the head and neck area. Exposure to sawdust and chemicals used in the leather industry, pesticides, and industrial solvents may increase the risk of a type of salivary gland cancer that occurs in the nose and sinuses. Salivary gland cancer is considered to be very rare, but when present, they are usually aggressive.

Symptoms and Diagnosis
A painless mass is the most common initial finding. Facial paralysis and pain are some of the symptoms of a parotid tumor that occur in more advanced lesions. Growth rate can be quite variable. A fine needle biopsy is then performed to determine whether the lesion is benign or malignant.

MRI scan of the face & neck with contrast is most helpful in assessing the size and extent of the tumor. The decision to get other studies including CT scans and PET scans will be dependant on the particular type and extent of tumor.

Biopsy with a Fine (Very Small) Needle Aspiration
Table 1
Salivary Gland
Malignancy Rate
Parotid
20%
Submandiublar
50%
Sublingual/Minor
65%

80% of tumors in the parotid glands are benign, while only 50% are benign in the submandibular gland, less than 35% in the minor salivary glands. Benign tumors include Pleomorphic adenoma, and Warhtin’s tumor. Both have a tendency to continue to grow and possibly affect the surrounding nerves. They require close monitoring and ideally need to be surgically removed since as they get larger the risk of injury to the nerves gets larger. Additionally, pheomorphic adenomas that are left unchecked have the potential of transforming into a more aggressive cancer over several years (Carcinoma ex-Pleomorphic, which is extremely destructive and has a poor cure rate).

Malignant tumors include:
  1. Mucoepidermoid Carcinoma is the most common malignancy in the parotid gland. It can be low grade, which is slow growing, and relatively less aggressive, which makes it easily treatable through a complete surgical excision. The high grade variant is very aggressive and requires immediate attention. The treatment of choice is complete surgical excision with an adequate margin of tissue (meaning the tumor and a rim of normal tissue measuring close to half an inch around the tumor), and if possible sparing the surrounding nerves if possible (however, often times the proximity of the tumor to the nerve does not allow the nerve to be preserved while achieving a complete tumor resection). Most often this is followed by post-operative radiation therapy.
  2. Acinic Cell Carcinoma or Oncocytic Carcinoma is the only salivary malignancy that has the potential of occurring on both sides. This tumor tends to also be relatively less aggressive than other salivary cancers and has lower potential for spread, as such if the diagnosis is made early and the tumor is surgically removed completely the chance of cure is high.
  3. Adenoid cystic Carcinoma is the most common cancer in the submandibular, sublingual, and minor salivary glands. It is an aggressive cancer that has a relatively high incidence of recurrence (return of tumor) after treatment and a relatively high incidence of distant metastases (spread to other parts of the body). It also tends to spread along nerves (peri-neural invasion) or through the bloodstream. It only spreads to the lymph nodes in about 5% to 10% of cases. The most common place of metastases (spreading) is the lung. As such this tumor needs to be treated very aggressively when diagnosed before it has the opportunity to spread elsewhere, and to decrease the chance of its return. Surgery is indicated in all cases except those patients who are physically healthy enough to undergo surgery, or in the very advanced cases. At the Center our team of experts immediately evaluate the patient and decide on the most appropriate surgical course and if necessary reconstructive option.Post-operative radiation therapy is indicated in most cases; neutron beam radiation therapy has been reported to have the best outcomes in treating this particular type of tumor, however, radiation alone is not enough to achieve cure in most cases. Another unusual fact about this cancer is that even after the tumor has recurred or spread, patients may still have long survival period. So treatment of this particular type of tumor is challenging and must be performed by head and neck surgeons, oncologists, and radiation oncologists quite familiar with the character of this tumor.
  4. Squamous Cell Carcinoma rarely originates in the saliva glands; most often squamous cell cancers spread to the parotid gland from skin cancers in the temple, scalp, ear and cheek areas. Treatment involves not only removing the parotid gland but also investigating the site of origin of this particular tumor and treating the primary site as well. Without a careful assessment of the site where this tumor may have originated from, the treatment will be incomplete. Often times a neck dissection (removal of lymph nodes in the neck area) needs to be done to assure complete removal of microscopic cancer cells that may have spread to the lymph nodes of the neck.
  5. Carcinoma Ex-Pleomorphic Adenoma is a cancer that arises from a pleomorphic adenoma that has not been removed for years and years. This is a particularly aggressive tumor that does not respond well to chemotherapy or radiation therapy. The treatment of choice remains radical surgical excision. The telltale sign of this tumor is having a lump in saliva gland for years and years followed by a sudden rapid growth. These tumors need to be addressed immediately without any delay.
  6. Other less common tumors include Adenocarcinoma, Polymorphous low-grade adenocarcinoma, Oncocytic carcinoma (malignant oncocytoma), Clear cell carcinoma, Epithelial-myoepithelial carcinoma of intercalated ducts, Undifferentiated carcinoma, and Lymphomas.

All these malignancies need to be treated immediately as the risk damage to the surrounding nerves (specifically the facial nerve) increases with advancement of the tumor.

Treatment

Surgical excision of the tumor and the gland is the primary mode of the treatment for a salivary gland tumor. Parotid surgery is made safer by the use of intra-operative EMG monitoring to measure the function of the facial nerve at all times.

In some cases when the tumor is superficial only the superficial lobe of the gland needs to be removed (superficial parotidectomy), which means removing the part of the gland sitting on top of the Facial Nerve, decreasing the risk to the nerve. Superficial parotidectomy is often performed on an outpatient basis (patients go home after surgery). In cases of larger tumors the surgeon attempts to find all branches of the Facial Nerve, and if the tumor permits, preserve the branches and remove the tumor from in between these branches. Depending on the pathology and stage of the tumor, at times, a neck dissection (removal of the lymph nodes in the anterior aspect of the neck) may need to be performed.

Facial Nerve Monitor

Enlarged Lymph Node in the Neck

To minimize scarring, we have developed a two-team approach of working with facial plastic and reconstructive surgeons to ensure the best possible aesthetic outcome. If the tumor permits we use a facelift approach, which hides the incision in the hairline.

Any defect that is caused by the removal of the tumor is almost always reconstructed immediately, to assure facial harmony and symmetry.

Face-lift Incision 3 Days After Surgery

Face-lift Incision 3 weeks after Surgery

In cases of tumors that have caused facial paralysis, our reconstructive team immediately reconstructs and if appropriate, will proceed with facial reanimation procedures at the same time, to improve the movement of the facial musculature. For more serious/aggressive salivary gland cancers, radiation therapy is recommended in addition to surgery, or for patients who are poor candidates for surgery. Adenoid cystic carcinoma has been reported to have a much better response rate to neutron beam radiation, which we advocate for our patients when possible.

Almost all tumors of the salivary glands require surgical removal. It is imperative that the diagnosis is made immediately to plan the appropriate course of action. Any delay in starting treatment not only compromises success rates but also increases the risk of injury to the surrounding nerves as well as leading to other complications.

Close follow up of patients on a regular basis is imperative for a variety of reasons: 1. The treatments are often rigorous and the effects are profound both physically and psychologically; a close relationship between the patient and the head & neck surgeon assures all the early and late side effects of therapy are dealt with appropriately, and some even avoided. 2. Close monitoring and appropriate surveillance allows early detection of a cancer if it recurs, thus allowing us to have an opportunity to successfully treat the tumor, and also detect it early enough so that the treatment may be minimal.

Patient Testimonials for our Otolaryngology Practice, Dr. Larian

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