Salivary Glands and Tumours of Salivary Glands

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Salivary Glands and Tumours of Salivary Glands

The salivary glands make saliva and release it into the mouth. Saliva contains enzymes that help digest food and also has antibodies that help protect against infections of the mouth and throat. There are 3 pairs of major salivary glands:

  • Parotid glands : These are the largest salivary glands and are found in front of and just below each ear. Most major salivary gland tumours arise in this gland. Majority of them (80%) are benign. 20% of parotid gland tumours are found to be malignant.
  • Sublingual glands : These glands are found under the tongue in the floor of the mouth.
  • Submandibular glands : These glands are found below the jawbone.
  • There are also hundreds of tiny (minor) salivary glands lining the mucosa of the oral cavity , nose, and larynx and they can be seen only with a microscope. Tumours of the minor salivary glands have higher risk of malignancy. About 80 % of minor salivary gland tumours are found to be malignant. Most small salivary gland tumours begin in the palate (roof of the mouth).
  • More than half of all salivary gland tumours are benign (not cancerous) and do not spread to other tissues.
Salivary Glands
parotid-surgery

    Salivary gland cancer is a rare disease in which malignant (cancer) cells form in the tissues of the salivary glands. Being exposed to certain types of radiation may increase the risk of salivary cancer. Signs of salivary gland cancer include a lump and or difficult in swallowing. Salivary gland cancer may not cause any symptoms. It may be incidentally noticed during a regular physical exam.

  • Superficial Parotidectomy : Facial nerve courses through the substance of the gland.The part of the parotid gland superficial to the plane of the nerve is called the superficial lobe and likewise the part deep to the nerve is called the deep lobe of parotid nerve.Superficial parotidectomy can be defined as excision of parotid tissue that lies lateral to the plane of the facial nerve and its branches. Most benign and malignant parotid tumours can be adequately treated with this procedure. No specific preoperative preparation is necessary, but patients must be counselled about complications such as temporary and permanent damage to the facial nerve, numbness, gustatory sweating, seroma, hematoma, and cosmetic changes.
  • Usual Symptoms are as follows
    • A lump (usually painless) in the area of the ear, cheek, jaw, lip, or inside the mouth.
    • Difficulty in swallowing
    • Difficulty in opening the mouth widely.
    • Numbness or weakness in the face.
    • Pain in the face that does not go away.
    • The following procedures are used for diagnosis of salivary gland tumours:
  • Physical exam and history : The head, neck, mouth, and throat are checked for signs of disease, such as lumps or anything else that seems abnormal. A history of the patient's presenting complaints and other health conditions is noted.
  • MRI (magnetic resonance imaging) Scan
  • CT scan
  • PET CT scan (Positron emission tomography scan) : A scan to find malignant tumour cells in the body. A small amount of radioactive glucose (FDG glucose ) is injected into a vein. Malignant tumour cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.
  • Biopsy: :
  • Fine needle aspiration (FNA) biopsy :The removal cells from the lump using a thin needle. An FNA is the most common type of biopsy used for salivary gland cancer.
  • Open biopsy : Rarely an open biopsy may be needed for diagnosis. An incision (cut) is taken on the skin and small sample of the tumour is taken for pathological examination.
  • Excisional Surgery : Very rarely if histology/cancer cannot be diagnosed from the sample of tissue removed during an FNAC or an incisional biopsy, the mass may be removed and checked for signs of cancer.

Stages of Salivary Gland Cancer
KEY POINTS

  • After salivary gland cancer has been diagnosed, tests are done to find out if cancer cells have spread within the salivary gland or to other parts of the body.
  • After histological diagnosis by FNAC and documentation of spread using scans like MRI /CT scan we arrive at the stage of cancer. TNM staging is the most commonly used staging system. Prognosis depends on the histology of the tumour and stage of the tumour. Early cancers have good prognosis whereas advanced stage III and IV cancers carry poor prognosis. Minor salivary glands are staged differently from the parotid, submandibular, and sublingual glands.
  • Management of Salivary Gland Cancers: Surgery remains the mainstay of management of salivary gland tumours. Adjuvant radiotherapy is advised after surgery in patients with advanced stage III and IV cancers to destroy any microscopic tumour cells in adjoining areas and lymph nodes.