What is a desmoid tumour?
A desmoid tumour belongs to the group of fibromatoses, which form on the muscle sheaths (the so-called muscle fasciae). Although a desmoid tumour is a benign tumour, it tends to grow into the surrounding tissue and is therefore clinically considered an aggressive soft tissue lesion. The desmoid tumour may regress spontaneously or grow slowly, causing painful inflammation, affecting organ function of adjacent organs or limiting limb mobility.
Desmoid tumour is a very rare disease with an incidence of 1 in 4 million. Women are more likely than average to develop a desmoid tumour in the abdomen after pregnancy. If the desmoid tumour develops in children or adolescents, the extremities or the head and neck area are mainly affected. In principle, however, a desmoid tumour can develop in almost all soft parts of the body.
What are the causes for the development of a desmoid tumour?
Doctors have not yet been able to prove beyond doubt the causes for the development of a desmoid tumour. However, they assume that the hormone oestrogen plays a role, as a desmoid tumour usually develops after pregnancy and often spontaneously regresses during menopause. It has also been found that the desmoid tumour develops due to injuries in the scar tissue.
What symptoms does a desmoid tumour cause?
The specific symptoms caused by a desmoid tumour always depend on its location and size. In general, a desmoid tumour may be noticeable by the formation of a firm, painless lump, or swelling in the arms, legs, chest, neck or abdomen. In some cases, the lump or swelling can also cause pain and should definitely be clarified by a doctor, especially if the lump or swelling grows to a size of more than 5 cm.
A growing desmoid tumour can displace normal tissue because it develops in elastic, flexible tissues or in deep spaces of the body. Therefore, before the tumour causes the first symptoms, it may have already grown to a considerable size. The following rather non-specific symptoms may indicate a desmoid tumour:
- Pain, which may be caused by the pressure of the tumour on nearby muscles, nerves and/or blood vessels,
- Tingling sensation, which may be caused by the pressure of the tumour on the local blood vessels or nerves,
- Restrictions in mobility in the feet or legs, for example limping,
- Problems moving the hands or arms
How is a desmoid tumour diagnosed?
To diagnose a desmoid tumour, a number of tests are usually carried out, which are also used to determine the size of the tumour and whether it is growing. The following imaging techniques may be used for this purpose:
- Magnetic resonance imaging (MRI): before the scan, the patient is given a special contrast agent to produce a clear image of the body. An MRI is ordered especially if abdominal wall and extra-abdominal desmoid tumours are suspected. An MRI may also be done after surgery to see if the tumour has re-formed.
- Computed tomography (CT): This uses X-rays to create images of the inside of the body from different angles. A computer then compiles these images into a detailed, three-dimensional picture to show abnormalities or tumours. A CT scan can be used to visualise the size of a tumour in particular.
- Ultrasound: Ultrasound uses sound waves to create an image. An ultrasound is particularly effective for examining lumps or organs in the body that are under the skin.
However, a biopsy is usually the only sure way to diagnose a desmoid tumour. For this purpose, a tissue sample of the tumour is taken and then examined in the laboratory.
In most cases, it is advisable to observe the tumour for the time being after the diagnosis has been made, as it will spontaneously regress on its own or stop growing. For this reason, treatment is not always absolutely necessary.
How is the desmoid tumour treated?
Shortly after a desmoid tumour is diagnosed, treatment is usually started to relieve the symptoms. Doctors refer to this as "supportive care", which is usually maintained throughout the treatment period. Since the hormone oestrogen plays a role in the development of the desmoid tumour, the tumour responds to anti-hormonal therapy in many cases. Drug therapy, for example consisting of anti-inflammatory drugs, is also always carried out if the tumour is inoperable.
Surgical removal of the desmoid tumour can also be considered. However, the prerequisite for surgery is always that the removal of the tumour does not impair the function of limbs or organs. If the tumour could not be removed completely, it should be followed by radiotherapy.
What is the prognosis for a desmoid tumour?
The desmoid tumour often forms again, i.e. it has a relatively high recurrence rate. This is especially true if the desmoid tumour could not be completely removed. If the desmoid tumour recurs, the patient is usually treated with medication.
A desmoid tumour cannot always be surgically removed and is therefore under medical control for a long time. As long as it does not affect organ functions, it is unproblematic for patients to live with a desmoid tumour. However, the tumour must be checked regularly.