The parotid glands are a pair of wedge-shaped salivary gland, found on either side of the mouth anterior to the ears along the cheek. It is the largest salivary gland. It secretes saliva through the parotid duct into the oral cavity. This in turn helps is mastication and easy swallowing. A number of important structure passes through the parotid glands, such as: Facial nerve, retromandibular vein, external carotid artery, superficial temporal artery, branches of greater auricular nerve, maxillary artery. Considering its anatomy, the parotid glands are prone to conditions such as parotitis, fibrous reaction, salivary stones, injury, cancers and parotid tumors.
What are Parotid Tumors or Parotid Mass?
Parotid tumor or parotid mass is a condition characterised by abnormal growths within the parotid glands. They are of 2 types:
- Benign or non-cancerous
- Malignant or cancerous
In certain cases, the growth inside the parotid gland may not originate from parotid tissues but originate from enlarged lymph nodes which invade the glands.
The most common types of parotid tumor or parotid mass are:
- Pleomorphic Adenoma: It is the most common variety of parotid tumor or parotid mass. It is a benign tumor that grows slowly within the parotid gland.
- Warthin's Tumor: It is the second most common type of parotid tumor or parotid mass. This is also a benign tumor and it can affect both sides of the face.
- Cancerous/Malignant Tumor: These are rare tumors and these can be slow growing or fast growing.
Other benign tumors include monomorphic adenoma and oncocytoma.
Symptoms of Parotid Tumors or Parotid Mass
Parotid tumor or parotid mass often present itself as a painless growing mass. It commonly occurs at the tail end of the gland as a localized mass. Pain may develop at a later stage, secondary to suppuration, haemorrhage or infiltration from adjacent tissues. The most commonly noted symptoms of parotid tumor or parotid mass include:
- A palpable mass or lump noted over the face
- Numbness over the affected gland
- Weakness over facial muscles/ progressive facial muscle paralysis
- Pain or swelling over the affected site can be a symptoms of parotid tumor or parotid mass
- Asymmetry between left and right side of the face can also be a symptom of parotid tumor or parotid mass.
Symptoms associated with facial palsy may indicate malignancy. Other clinical features that may indicate malignancy are as follows:
- Fixed mass
- Hardness with rigidity
- Involvement of surrounding tissues and adjacent structures such as facial nerve, lymph nodes etc.
- Ulceration of overlying skin
- Cranial nerve palsy.
Epidemiology of Parotid Tumors or Parotid Mass
Studies have shown that 65-70% of salivary gland tumors are benign and 80% of parotid gland tumors or mass are benign. Pleomorphic adenoma is more common among women whereas Warthin's tumor is more common among older men. Malignant tumors are common between the ages of 50 to 60 years.
Causes and Risk Factors of Parotid Tumors or Parotid Mass
Possible causes of parotid tumor or parotid mass include:
- Abdominal surgery
- Liver cirrhosis
- Salivary duct occlusion or stones
- Salivary gland infections
- Underlying conditions such as sarcoidosis, Sjogren's syndrome etc.
- Metastasis of cancer from other areas.
Other risk factors include:
- Exposure to Radiation as a Risk Factor for Parotid Tumor or Parotid Mass: Radiation therapy to areas around the parotid gland increases the risk of parotid tumors or parotid mass.
- Smoking can Increase the Risk for Parotid Tumors or Parotid Mass: It has been noticed that the incidence of parotid tumor is more among chronic smokers than non-smokers.
- Use of Mobile Phone as a Risk Factor for Parotid Tumor or Parotid Mass: Some studies have suggested that the risk of parotid tumor or parotid mass increases with increased use of mobile phone.
- Other Risk Factors: Other possible risk factors for parotid tumor or parotid mass include genetic inheritance, injury, trauma, aging etc.
Complications of Parotid Tumors or Parotid Mass
Benign parotid tumor or parotid mass if left untreated can become malignant over a period of time. Parotid tumors can cause facial deformations and anaesthetic appearance. It can grow in size and affect the surrounding structures and tissues. Over a period of time, parotid tumor or parotid mass can involve the underlying nerves, lymph nodes, blood vessels, muscles, skin and even bone leading to irreversible damage. In advances cases, the malignancy can metastasize to other areas of the body.
Diagnosis and Investigations for Parotid Tumors or Parotid Mass
A thorough clinical examination is done by an experienced physician or an ENT specialist. An oral surgeon can also help in correct diagnosis of parotid tumors. A detailed case history is obtained followed by palpation of the gland and physical examination. In advanced cases, intervention by an oncologist and surgeon may be required. The suspect is then made to undergo a series of imaging studies and investigations. These include:
- Ultrasound to Diagnose Parotid Tumor or Parotid Mass: Ultrasonography helps in visualizing the deep lobe of the gland.
- FNAC (Fine Needle Aspiration Cytology) to Determine Parotid Tumor or Parotid Mass Type: Ultrasound guided FNAC is commonly done as a confirmatory test. CT-guided biopsy can also be considered.
- CT Scan to Investigate Parotid Tumor or Parotid Mass: A CT scan is done in cases of deep tissue invasion.
- MRI to Investigate Parotid Tumor or Mass: This is often done in cases of high malignancy.
- Sialography to Diagnose Parotid Mass: Specialized studies such as sialography or sialogram x-ray may be done for studying the salivary ductal system.
- Other Tests to Diagnose Parotid Tumor or Parotid Mass: In presence of other associated conditions such as Sjogren's syndrome, investigative studies such as salivary function test, eye test, and special blood work may be considered.
Treatment of Parotid Tumors or Parotid Mass
- Parotidectomy: Surgical intervention may be required for management of parotid tumor or parotid mass. This is done by partial or complete removal of the parotid gland depending on the severity of the condition. This procedure is known as parotidectomy. Most common indications for parotidectomy includes mass in the gland; chronic infection of the gland; and obstruction of flow of saliva.
- Removal of Lymph Node: If the parotid tumor or parotid mass affect the lymph node, surgical removal of the lymph node via neck dissection may be required.
- Reconstructive Surgery to Manage Parotid Tumor or Parotid Mass: After the primary surgery, a second surgery may be required to reconstruct or repair the damaged area. This is done using grafts.
- Radiation Therapy to Treat Parotid Tumors: If surgical intervention is not possible, radiation therapy is used to arrest growth of cancerous cells.
- Chemotherapy for Treating Parotid Tumors or Parotid Mass: In advanced cases, when the cancer spreads to other area, drug treatment called chemotherapy is used to arrest further growth and spread of cancer.
Surgical intervention may have certain risks involved, such as:
- Post-surgical facial weakness/facial nerve injury
- Numbness and loss of sensation
- Frey syndrome i.e. sweating and redness over face while eating
- Salivary fistula
- Bleeding, infection and delayed healing.
Prognosis of Parotid Tumors or Parotid Mass
The prognosis of parotid tumor or parotid mass is generally good, provided it is treated early. Most parotid tumors are benign and surgical removal of the affected portion cures the condition. In very rare cases, malignancy is an issue and may need advanced therapy.
Parotid tumor or parotid mass is a kind of salivary gland tumor that affects the parotid gland. It is characterized by a growing mass over the parotid gland. Most of the cases are benign; however, there is a small chance of malignancy. It is diagnosed by thorough physical examination followed by investigative studies such as ultrasound, CT scan, MRI, FNAC and biopsy. Early treatment and diagnosis of parotid tumor or parotid mass limits the possibility of malignancy. Treatment involves surgical removal of the affected portion. In advanced cases, radiotherapy and chemotherapy may be required. Parotid tumor or parotid mass is a treatable condition, provided it is diagnosed early and treated rightly.