The Parotid gland is the salivary gland which is situated laterally near the mandible. Approximately 75% of neoplasm of salivary glands occur in the parotid glands. 80% of parotid tumours are benign and of these 80% are called pleomorphic adenomas.
Classification of parotid tumours:
- Any age, no gender predilection
- 75% of all parotid tumours
- Over 60 years of age
B) Warthin's tumour
- Over 60 years
- Male to female ratio is 4:1
- Acinic cell Carcinoma:
Low grade malignancy
- Adenoid Cystic carcinoma: Commonly seen in USA.
Invariably fatal due to perineural spread and pulmonary metastasis
- Adenocarcinoma and Squamous Cell Carcinoma: Both have poor prognosis. Very rare. 25% have
5 year survival
3. Non epithelial
- Mostly infants affected. Frequent spontaneous regression of any gland affected in this group.
4. Malignant lymphoma
5. Unclassified tumour
What are the characteristic features of parotid tumours?
- All parotid neoplasms are radioresistant
- No formal biopsy should be performed in parotid tumours except in tumours of ectopic salivary gland e.g. palatal salivary gland
What are the criteria indicating malignant change in mixed parotid tumour?
- Sudden and rapid increase in size
- Painless tumour becomes painful and tender
- Feels stony hard
- Growth becomes fixed to the deeper structures e.g. masseter, mandible
- Overlying skin may become fixed to the swelling and looks and feels reddish blue and hot
- Evidence of facial nerve involvement causing asymmetry of face and difficulty in closing the eye
- Areas of anaesthesia over the skin
- Jaw movements become restrained
- Veins over the swelling become prominent
- Enlargement of cervical lymph node
- There may be evidence of disseminated blood borne metastasis
What is the treatment of parotid tumours?
Outlined here is the treatment of parotid tumours:
- Benign: Superficial parotidectomy.
- Malignant: Radical parotidectomy or total conservative parotidectomy.
- Malignant metastatic lymph nodes may be treated by radical neck dissection or by radiotherapy.
What is the differential diagnosis of parotid swelling?
Differential diagnosis of parotid swellings:
- Winged mandible
- Masseteric hypertrophy
- External carotid aneurysm
- Pre- Auricular lymph node