Salivary glands are classified in two groups as major and minor glands. At the both sides, the parotid salivary glands (in front of and below the ear); the submandibular salivary glands (below the lower jaw); and the sublingual salivary glands (under the tongue) are major salivary glands. There are many minor salivary glands in the mouth, lips and palate. The function of the salivary glands is to produce saliva, a watery substance that moisturizes the mouth, shows a disinfectant effect against germs and contains proteins called ‘digestive enzymes’. Through the major and minor glands, 0.5 to 1.5 liters of saliva per day is produced and discharged into the mouth.
Diseases in this group are qualified in two sub-groups as tumoral (i.e. progresses with mass formation) and non-tumoral diseases. The most common diseases within the scope of this classification are as follows:
1. Acute Salivary Gland Inflammations
i. Viral Inflammations Mumps is the most common viral salivary gland disease. This disease usually affects the parotid salivary glands located in front of and below the ear and usually observed in children 4-6 years of age. The virus transmitted through air and disease shows itself initially with pain, swelling, tenderness and fever under the ear at the both sides, 14 to 21 days after virus’s entering the body. Difficulty in opening the mouth may develop due to spasms in the muscles around the parotid gland. Diagnosis is made by reviewing the history and observing antibodies produced by the immune system against the mumps virus existing in the blood. It does not require any special treatment. Rest, fluid intake and antipyretic and analgesic medications are usually adequate. Rarely complications may develop due to cases in which the virus affects the brain, kidney, internal ear or testicles. In such a case, special therapies may be required for the affected organ. The incidence of mumps significantly declined with the beginning of the implementation of mumps vaccine.
ii. Bacterial Inflammations This disease that is often observed in the parotid gland appears with suddenly emerging pain and swelling in front of and below the ear as well as redness and tenderness in the skin. It is usually observed in elderly people with a weak immune system, who intake inadequate amount of fluid, typically during postoperative periods that require inpatient treatment. In examination, purulent discharge is observed in the areas where the ducts of the salivary glands open to the mouth. In case of delayed treatment, it may lead to life-threatening infections due to abscess formation or spread of inflammation, especially in elderly people. Treatment is administered with antibiotics determined based on the culture taken from the salivary duct.
2. Chronic Salivary Gland Inflammations It is a type of inflammation, progressive in the course of time, which occurs generally in consequence of decreased saliva production and accumulation of dark secretion in the salivary ducts. The slowdown of the saliva secretion causes the bacteria—normally found in the mouth—to spread from inside the duct towards the salivary gland. Chronic inflammation changes the structure of the salivary duct as well as the structure of its secretion and causes the problem to be permanent over time. Stones that stay in the channel for a long time may cause the development of this problem as well.
Recurrent acute inflammations, weaknesses of the body's immune system, radiation therapies, smoking, and oral hygiene disorders may pave the way for this disease. The most evident symptom is painful swelling that increases during eating; on the other hand, usually signs of acute inflammation such as fever and redness do not occur. The treatment involves increasing fluid intake, helping the discharge of the secretion with massage, administering antibiotic treatment in acute inflammation. Sialendoscopic evaluation of the gland’s ductal system, lavage and topical steroid applications may also be helpful. Surgical removal of the salivary gland is performed in cases where the patient does not respond to other treatment modalities.
Dryness of the Mouth (Xerostomia) Dryness of the mouth may also lead to certain problems such as weakness in the sense of taste, difficulty in swallowing, pain and tooth decays. This problem that can be encountered in parotid gland diseases may also develop due to some factors such as stress, diabetes, chronic inflammations, autoimmune diseases like Sjogren’s Disease and radiation therapy. The treatment involves threating the disease that causes the problem, increasing fluid intake, using drugs that increase saliva secretion and using artificial saliva.
3. Salivary Gland Stones (Sialolithiasis): This subject is discussed under the subject topic Salivary Gland Stones
1. Benign Salivary Gland Tumors
70-80% of tumors originating from the salivary glands originate from the parotid salivary gland and 80% of parotid tumors are benign tumors; whereas the incidence rate of tumors observed in the submandibular salivary gland is 15%, with a benign rate of 50 to 60%; and the incidence rate of tumors in minor and sublingual salivary glands is about 10%, with a benign rate of 35%.
Tumors originating from the salivary glands usually appear as slowly growing masses at the ages of 50-70. Examination and radiological tests as well as fine needle biopsy take an important place in diagnosis. With needle biopsy enables knowing if the tumor is benign or malignant and then the treatment is planned accordingly.
Most of benign salivary gland tumors are a type of tumor called mixed tumor or pleomorphic adenoma mostly seen in women between the ages of 30 and 60. In general, surgical treatment is administered in cases of all benign tumors. During this surgery the salivary gland where the tumor is located in is removed as a whole. An important feature of the parotid salivary gland is that the facial nerve moving the facial muscles passes through these glands and branches there when it leaves the lower part of the ear bone and then enters the facial muscles. The part of the gland above the nerve and its branches is called the 'superficial lobe' and the part of the gland under the nerve is called 'deep lobe'. If the deep lobe is not involved by the tumor in cases of benign parotid tumors only the superficial lobe is removed during surgery.
2. Malign Salivary Gland Tumors
Malignant salivary gland tumors seen in the head and neck region constitute 3-4% of malignant tumors. Although the causes of the development of these tumors are not known exactly, viral infections, exposure to radiation, environmental factors and genetic characteristics are thought to be effective in this regard.
Malignant salivary gland tumors are observed to exist most commonly (75-80%) in the parotid gland, in the submandibular salivary gland (15-20%), and rarely in the sublingual or minor salivary glands.
Many different types of tumors can be seen in the salivary glands; however, the most common ones are mucoepidermoid carcinoma (45%) and adenoid cystic carcinoma (22%). Malignant tumors are classified as low, medium and high-grade tumors, depending on their clinical behaviors, spreading speeds and the extent of their structural changes.
High-grade tumors are more aggressive tumors posing a higher risk of distant metastasis, which tend to spread to surrounding tissues and cervical lymph nodes. Surgery is the first option for the treatment of malignant tumors in the salivary glands. During surgery, the tumor should be removed extensively in such a way as to include normal, i.e. metastasis-free tissues surrounding the tumor.
Important structures such as the facial nerve passing through the surgical site and the lingual nerves should be protected, as long as there is no involvement by the tumor. During surgery, neighboring lymph nodes are also removed (neck dissection surgery) in cases of tumor metastasis is detected in the cervical lymph nodes and also in cases where the tumor is highly likely to spread to the cervical lymph nodes, even if no significant symptom has been detected.
Radiotherapy can rarely be selected as the main treatment for salivary tumors. In high grade tumors, highly likely to spread, radiotherapy is administered after the surgery to the surgical site with intent to prevent recurrence of tumor formation in the same area.
Drug treatment (chemotherapy) can be preferred for patients, who are inoperable due to other health problems and for patients in whom the tumor has expanded in the region and/or has spread to distant organs.