What is fibrosarcoma?

Fibrosarcoma or fibroblastic sarcoma is a malignant cancer that originates from connective tissue cells. In principle, not only humans but also animals (especially mammals) can contract this form of cancer. Cats in particular often suffer from fibrosarcoma, as it is one of the most common skin tumours in them. Although fibrosarcoma is less common in humans than in other types of cancer, it can develop at any age and may be congenital. Doctors therefore distinguish between congenital and infantile fibrosarcomas, which can appear in children up to the age of 5, and an adult form of fibrosarcoma. On average, men over the age of 50 are more likely to develop fibrosarcoma than women, although the adult form of fibrosarcoma is still rather rare at around two per cent. Children, on the other hand, are more likely to develop fibrosarcoma, with an average of ten per cent.

How does a fibrosarcoma develop?

A fibrosarcoma is characterised by its immature fibroblasts or anaplastic spindle cells. Fibroblasts are the cells that make up a major part of connective tissue and play an important role in the synthesis of intercellular substance. As a rule, fibrosarcoma usually forms on the legs, but it can also develop on the arms and back. Since the cancer cells also reach the organs via the bloodstream, fibrosarcomas often form metastases there.

What are the causes of fibrosarcoma?

So far, doctors have not been able to identify the clear causes that contribute to the development of fibrosarcoma. However, it is suspected that the following factors may favour the development of fibrosarcoma:

• (frequent) contact with asbestos, dioxin and/or polyvinyl chloride,
• Radiation therapy given for a previous cancer,
• unhealthy lifestyle, such as excessive smoking and/or alcohol consumption, poor and high-fat diet and/or little to no physical activity.

How does fibrosarcoma develop in animals?

As in humans, fibrosarcoma in animals can occur in any part of the body. However, it is noticeable that fibrosarcoma develops particularly in those areas where vaccination has previously been carried out. This is supported, among other things, by the fact that certain subtypes of the FeLV vaccine have also been detected in the tissue of fibrosarcomas.

What symptoms does a fibrosarcoma cause?

The specific symptoms caused by a fibrosarcoma always depend entirely on its location. Usually, however, a fibrosarcoma does not cause any specific symptoms, especially in the early stages, which makes early diagnosis difficult. Another complicating factor is that, unfortunately, misdiagnoses and mistreatments are usually carried out. All this leads to the fact that fibrosarcoma is usually diagnosed late and has already spread to metastases by that time.

Patients with fibrosarcoma complain of (painful) nodules under the skin at a fairly advanced stage. Often, these lumps can take on a reddish to brownish colour and cannot be moved. In some cases, ulcers and swelling of the lymph nodes may also occur. Many patients also complain of severe fatigue and/or exhaustion and/or unnatural pallor. If fibrosarcoma continues to grow undetected and untreated, it can also lead to unwanted weight loss.

When should a doctor be consulted?

If there are unusual swellings, lumps, growths or changes in the tissue structure, these should always be clarified by a doctor. This applies all the more if these unusual skin changes increase in intensity, extent and/or size. If, in addition, pain develops and the patient feels generally unwell and/or uncomfortable, a doctor should be consulted in any case.

How is fibrosarcoma diagnosed?

If the swelling appears and grows quickly without any previous injuries, there may be a reasonable suspicion of fibrosarcoma and it should therefore be clarified by a doctor. In order to make a diagnosis, the doctor will first examine the tumour using the usual imaging methods such as ultrasound, a computer and/or magnetic resonance tomography and determine whether the tumour has already metastasised. In contrast to other benign cancers, a malignant tumour is usually quite well supplied with blood. Since fibrosarcomas often metastasise to the lungs, the doctor will usually also do an X-ray of the lungs after confirming the diagnosis. In addition, a tissue sample may be taken and a biopsy performed. This is done by first removing tissue from the tumour using a needle and sending it to a pathologist for further clarification.

How is fibrosarcoma treated?

Fibrosarcoma is usually removed surgically. To prevent the fibrosarcoma from regressing, chemotherapy and/or radiotherapy is given after the operation. If, on the other hand, the fibrosarcoma is already in an advanced stage and has possibly already spread to metastases, it will no longer be possible to surgically remove all tumour sites. Instead of a curative therapy, the patient will be prescribed appropriate pain-relieving medication.

What are the prospects of a cure for fibrosarcoma?

The chances of a complete recovery from fibrosarcoma are rather poor, both in humans and in animals. This is usually due to the fact that fibrosarcomas are diagnosed rather late. If, on the other hand, they are detected and treated at an early stage, the chances of recovery improve accordingly.

Basically, the further a fibrosarcoma has spread in the connective tissue, the worse the prognosis for a complete cure. This is even more true if metastases have already formed. In this case, the treatment of the patient is focused on life-prolonging measures and the reduction of existing pain.