What is a monomorphic adenoma?

This type of adenoma is a benign tumour of the parotid gland. This tumour is rather a rare type of tumour in the category of salivary cell tumours. Tumours in the area of the parotid gland, which are arranged in pairs on the ear and are located behind the cheek, usually only grow very slowly and do not cause any pain. However, the first signs are swelling, sometimes facial paralysis and pain in the area around the parotid gland.

Especially often such tumours develop after a salivary gland inflammation has subsided. Although 80 % of these tumours are benign, it is still advisable to have any of the parotid gland tumours removed . This is because the larger the tumour, the more difficult it becomes to operate and an initially benign tumour that is not treated can develop into a malignant one in a very short time.

How does a monomorphic adenoma develop?

The largest salivary glands in humans are located behind the cheek bones, namely the parotid gland. Also included in the group of salivary gland tumours are the mandibular salivary gland tumours and the sublingual salivary gland tumours. Above all, chronic inflammation of the glands, salivary stones, bacterial infestation, but also chronic nicotine consumption and alcohol consumption are considered possible causes for the development of parotid tumours.

What are the symptoms of a monomorphic adenoma?

Since the benign parotid gland tumour usually grows very slowly on the outer lobe of the parotid gland, in most cases it is visible as a coarse, non-painful but movable lump and can be felt . Meanwhile, the tumour is in a closed capsule. Some patients complain of discomfort in the affected area and also dry mouth. Another symptom can also be paralysis of the visual field on one side.

How is a monomorphic adenoma diagnosed?

At the first examination, clinical diagnostics are carried out, during which the doctor palpates the swelling, examines the mouth and nose and the auditory canal. A fine needle biopsy is necessary to determine the nature of the tumour tissue . However, if there is a suspicion of a benign monomorphic adenoma, a biopsy is not performed at first. This is to avoid seeding the tumour cells . For imaging diagnostics, a sonography, CT and MRI are performed. Thanks to these examinations, the doctor gets information about the type, location and size of the tumour.

Since every monomorphic adenoma, whether benign or malignant, should be removed , a preoperative examination becomes necessary. Only a histological examination of the surgical specimen can provide information as to whether it is a benign or malignant change. In some cases, a frozen section diagnosis can be helpful during the operation. In the case of a benign growth , the remaining skin depression can be filled in during the tumour operation by the tissue of adjacent muscles. This has the great advantage that no further surgery needs to be performed. >/p> >h2>How is a monomorphic adenoma diagnosed?>/h2> >p>As already mentioned, parotid gland tumours must always be surgically removed, because even a benign one can change into a malignant one over time. The operation is problematic, because the facial nerve runs through the parotid gland, which consists of an inner lobe and an outer lobe. This nerve branches out and can be damaged. This nerve branches out and reaches into the area of the face that is responsible for facial expressions . During the operation, this nerve must not be damaged under any circumstances, and in many cases this is often very difficult because, depending on the location of the tumour, different areas of tissue have to be removed.>/p> <p

Subtotal parotidectomy: In the case of tumours that are located in the inner lobe or also part of large tumours that affect the outer part of the gland, the outer part of the gland is first removed, then the part of the parotid gland on the inner lobe with the tumour is removed. This procedure is highly complicated because it involves exposing the facial nerve.

Total parotidectomy: This therapy is used when the entire parotid gland with the tumour has to be removed.

Radical parotidectomy: In some cases, it is unavoidable that the facial nerve must also be removed. This can be largely restored in a subsequent operation.

Neck Dissection: If lymph nodes on the neck are affected, they also have to be removed . With a malignant tumour of the parotid gland, it is not uncommon for numerous lymph nodes, up to 30, to be affected by metastases.

How is a monomorphic adenoma followed up?

In benign tumours of the parotid gland and in most cases of a malignant tumour in childhood and adolescence, no further treatment measures are necessary after the operation . However, if it was not possible to remove the entire tumour during the operation, metastases of the tumour may have settled in other organs of the body , which can cause aggressive forms of tumour. Therefore, it is essential that chemotherapy or radiotherapy is given.

Especially radiotherapy has proven to be extremely effective for localised tumours . Particularly in the case of children, the benefits and consequences must be weighed up, because they usually react much more sensitively to radiotherapy than adults. Likewise, complications such as a growth disorder in the face and a second cancer occur much more frequently. As a result, radiotherapy is carried out rather less frequently. However, if the therapy is not unavoidable, radiotherapy is usually combined with chemotherapy.

What are the risks of monomorphic adenoma?

If the facial nerve is injured during the necessary operation and this is left untreated, facial paralysis will result. But here the risk is less than 1%. If saliva gets into the still open wound of the removed salivary gland tissue, this can lead to the formation of a salivary fistula, which, however, heals spontaneously in most cases.

Some sufferers also report sweating while chewing. The reason for this is that the fine nerve branches connect with the sweat glands in the course of up to 3 years after the operation. However, special ointments can help to correct the problem. After the removal of a benign or a malignant tumour of the parotid gland, a dent may remain. In the case of benign tumours, the missing tissue from an adjacent muscle can be inserted during the actual operation. The head turn muscle is excellent for this. If a malignant tumour is present, the main focus is first on treating the tumour; cosmetic corrections are only carried out later.

What is the prognosis for a monomorphic adenoma?

If the tumour can be completely removed, the prognosis is very good, because only in 5 % of cases does the tumour recur. Of course, the continued lifestyle also plays a major role here, such as abstaining from alcohol and nicotine.