Fibrosarcoma in cats - Symptoms, causes and treatment

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Feline fibrosarcoma or sarcoma associated with the injection site, is between the 6 and 12% of feline tumors. It is a mesenchymal tumor in which the fibroblasts of the connective tissue proliferate. It is a neoplasm very aggressive and with a great tendency to local recurrence. They appear as a small, rapidly growing lump or inflammation, however, they do not usually metastasize to other organs..

A great peculiarity of these tumors is that most appear after vaccination. Treatment consists of a combination of aggressive surgery with surgical margins, accompanied by chemotherapy and radiation therapy. To learn more about the Fibrosarcoma in Cats, Its Symptoms, Causes and Treatment, continue reading this AnimalWised article.

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  1. What is feline fibrosarcoma?
  2. Feline fibrosarcoma symptoms
  3. Causes of fibrosarcoma in cats
  4. Diagnosis of feline fibrosarcoma
  5. Treatment of feline fibrosarcoma
  6. Feline fibrosarcoma prevention

What is feline fibrosarcoma?

Fibrosarcoma is a malignant mesenchymal tumor in which fibroblasts proliferate, cells present in the connective tissue that generate collagen and intervene in healing. It is mesenchymal since it is a tumor of mesenchymal origin, a tissue that is formed in the embryonic state of the feline and that gives rise to supporting and connective tissues.

Feline fibrosarcoma presents a rounded, soft or solid appearance, and it can be uni or multinodular. Adhesions to nearby skin layers frequently occur. It is not a painful or ulcerated tumor, except in the final stage. Metastasis (arrival of cancer cells to other parts of the body) is rare, while recurrences of the tumor once removed are common.

Feline fibrosarcoma symptoms

Feline fibrosarcoma can appear at any age. However, it is more common in middle aged cats. Initially, the lump is very small and is noticeable when stroking the cat, but increases in size very quickly.

This mass can be relatively mobile and be fixed to the subcutaneous tissue and underlying musculature, with probable infiltration of the surrounding structures. This makes the space between the tumor and healthy tissue poorly defined. The inoculation area is most often the interscapular zone (between the shoulders and neck of the cat). Large masses may be injured or ulcerated.

On the other hand, if metastasis appears, which mainly occurs in the lung, they would appear respiratory disturbances.

Causes of fibrosarcoma in cats

In general, tumors appear as point genetic mutations. However, in the case of feline fibrosarcoma it can cause these causes:

  • Vaccination: after vaccination at the site of inoculation of the vaccine. Some cats develop a small inflammatory nodule at this point that disappears in about two to three weeks as a side effect of vaccination. If it does not go away, chronic inflammation can lead to the development of this tumor. This inflammation at the vaccine inoculation site occurs more frequently in vaccines with adjuvants, which are components that are added to vaccines to improve their effectiveness. The vaccines that most frequently contain adjuvants are those for rabies and feline leukemia..
  • External agents: other external agents in the subcutaneous tissue, such as microchips, lufenuron or long-acting antibiotics.
  • Feline sarcoma virus: Another less common cause is that the feline sarcoma virus, derived from the feline leukemia virus, gives rise to this type of tumor.

Diagnosis of feline fibrosarcoma

First of all, a differential diagnosis with an abscess at the injection site with an ultrasound and rule out feline leukemia virus infection from a test.

Cytology is not very useful in the diagnosis, being necessary the wedge incisional biopsy and its anatomopathological study. This biopsy should be performed in the presence of lumps of more than two centimeters and in those that have been present three months after inoculation or grow during month one of the same..

In the histology of the biopsy, an important inflammatory component will be seen, with proliferation of mononuclear cells, fibrosis and granulation. These sarcomas are characterized by high mitosis (cell division) activity and large central necrosis (cell death).

As well X-rays should be performed, especially of the thorax, to assess whether or not there is metastasis in the lung or other locations.

Treatment of feline fibrosarcoma

Fibrosarcoma treatment will depend on the size and location of the tumor and whether or not there is metastasis. In this way, the possible treatments would be:

  • Complete removal of the tumor: the main therapy will consist of the complete removal of the tumor, being convenient to remove all the muscles and fascia adjacent to the tumor, due to its great infiltrative capacity. Surgical margins of at least 2 cm are required, ideally 3-5 cm lateral and deep to the tumor mass, which may include the dorsal vertebral spinous processes and the dorsal edge of the scapula..
  • RadiotherapyRadiation therapy can be used, the irradiated area being the location where the tumor was before the incision and it should be done when healing has begun, a week or two after surgery. The efficacy of radiation therapy varies depending on the number of previous excisions, size before excision, and quality of surgical excision..
  • ChemotherapyChemotherapy can be 50-60% effective using carboplatin or doxorubicin. Non-vaccine associated feline fibrosarcomas have a lower response to chemotherapy, around 10-15%.

If there are metastases, aggressive surgery should not be performed.

Feline fibrosarcoma prognosis

The prognosis for feline fibrosarcoma is reserved, due to the high risk of recurrence. However, with a well done surgery, with chemotherapy and radiotherapy, the cat can live several more years.

Feline fibrosarcoma prevention

The incidence of this disease in cats increases the more they are vaccinated. However, the incidence of diseases and their fatal consequences is much higher than the risk of formation of this tumor, so you should not stop vaccinating.

To prevent difficulty in the removal of a tumor in the interscapular area, it is recommended vaccinate cats in other locations, as in the extremities or in the area behind the ribs. In this way, if this tumor appears in these areas, the limb can be amputated or a better excision can be achieved with the necessary margins in the case of the side.

This article is merely informative, at AnimalWised.com we do not have the power to prescribe veterinary treatments or make any type of diagnosis. We invite you to take your pet to the vet in the event that it presents any type of condition or discomfort.

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