What are the salivary glands?
Most of the saliva is produced by 3 couples of major glands: parotid, submaxillary and sublingual. Moreover there are minor salivary glands (between 600 and 1000) distributed through the mucous of the oral cavity, pharynx, larynx and nose.
All of them empty out the saliva in the mouth through conducts.
Can tumours grow on the salivary glands?
1 to 6% of the head and neck tumours grow on the salivary glands. The 80% of them originate on the parotid gland and a 10 to 15% grow on the submaxillary gland. 70-80% of the parotid tumours are benign as the 40-60% of the submaxillary gland tumours.
Due to the fact that the salivary glands contain a large number of different cells, there exist a vast variety of tumours both benign and malignant that can grow there.
Which are the symptoms?
One should contact a specialist if a lump appears on the salivary glands zone (on the jaw, in front of the ear, under the jaw, on the neck or the mouth floor).
How is it diagnosed?
The doctor palpates the zone and practices a fine needle aspiration to collect some cells (cytology). They also require medical imaging (tomography, MRI, sialography) to complete the study. Since there is a great diversity of derived tumours and tissues in the glands, this study will define the benignity of the tumour with a reliability of the 80%. The definitive diagnosis is not done until the surgery.
Which are the benign tumours of the salivary glands?
The most frequent (50-70%) is the mixed tumour or pleomorphic adenoma. Most of them (60-70%) grow on the parotid gland.
It is a rounded tumour of slow growth. Between 2-9% of the cases can become malignant, so surgery is always advised.
The second most common is adenolymphoma or Warthin’s tumour. It represents 5-10% of the parotid tumours (12% can be multifocal), it is of slow growth and asymptomatic. Other frequent benign tumours are:
- Oncocytoma (1%)
- Cystadenoma (2%)
- Basal cell adenoma
- Canalicular adenoma
- Sebaceous adenoma
- Sebaceous lymphadenoma
Which is the treatment?
The treatment is surgical.
If the tumour is in the submaxillary gland or the sublingual gland the whole gland will be extracted. If the tumour is in the parotid gland, there will be performed a superficial parotidectomy, except when the tumour is in the deep lobe, in which case a total parotidectomy with conservation of the facial nerve must be practised.
The parotid gland is divided by the facial nerve and its ramifications, which are distributed through the face in the same plane, in one superficial lobe and one deep lobe. Surgery of the parotid gland requires a great accuracy in identifying and dissecting the facial nerve and all its branches to preserve its function.
When the parotid gland is extracted the zone of the angle of the jaw will remain sunken. Dr Máiz uses the following techniques to prevent this facial asymmetry:
- SMAS flap (like in a facelift)
- Sternocleidmastoid muscle flap
- Grafting of fat extracted from the navel region.
In order to hide the scar, Dr Máiz practises the same incision as in a facelift.
Which are the malignant tumours of the salivary glands?
Malignant tumours represent 15% of all the tumours of the salivary glands. There are many types, depending on the tissue in which they originate:
- Mucoepidermoid carcinoma (35%)
- Carcinoma ex mixed tumour (5-20%)
- Adenocarcinoma (10-20%)
- Adenoid cystic carcinoma (6-15%)
- Epidermoid carcinoma (1-5%)
Which are the symptoms of malignant tumours?
If a lump on a major salivary gland which grows and hardens appears you should visit a specialist immediately. A great sign of the apparition of a malignant salivary gland tumour is pain on the area and facial paralysis.
How are they diagnosed?
By palpating the doctor will deem the tumour to be malignant if it is hard and cannot be moved. They will practice a fine needle aspiration, medical imaging (even of the neck to discard the existence of metastasis)
Which is the treatment?
Once the staging of the tumour is known (which depends on its size and whether it has affected surrounding tissues and lymphatic ganglions of the neck) the most adequate treatment will be decided.
Generally the treatment is surgical. A total extraction of the submaxillary or parotid gland will be practised preserving the facial nerve.
Depending on the results of the pathologic study of the tissues, the type of tumour and its aggressiveness, the patient will also be treated with radiotherapy. In general chemotherapy is of scarce utility to these patients.
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