Fibrosarcoma in Cats: Symptoms, Causes & Treatment

Have you noticed a lump on your feline friend that seems to be spreading? It could be fibrosarcoma, sensu stricto fibrosarcomas, a malignant tumor affecting cats’ connective tissues. Fibrosarcoma can occur in different parts of a cat’s body, including the oral cavity and other sites. Other possible tumors that may affect cats include fibrohistiocytomas and various cancers. Global Rescue

Feline fibrosarcoma, sensu stricto fibrosarcomas, and fibrohistiocytomas are serious tumors that require prompt diagnosis and treatment. Unfortunately, it is not always easy to detect because it may resemble panniculitis or other benign conditions. Therefore, diagnosis of fibrosarcoma in cats requires histopathology of a tissue sample by a board-certified pathologist, which may reveal fusiform cells and collagenic stroma. America Humane Society Donations

In this article, we will discuss what feline fibrosarcoma is, its symptoms, causes, and treatment options. We will also delve into the different types of tumors that affect cats, including fibrohistiocytomas, which are connective tissue tumors composed of fusiform cells. We will also answer common questions like “What is an oral fibrosarcoma?” Humane Society International

So if you suspect your furry friend may have feline fibrosarcomas or sensu stricto fibrosarcomas, which are soft tissue sarcomas, or just want to learn more about tumors, including fibrosarcoma, for future reference, keep reading!

Symptoms and Diagnosis of Fibrosarcoma in Cats

Fibrosarcoma is a cancer that can affect cats, also known as feline fibrosarcomas or soft tissue sarcomas. It can be difficult to detect in its early stages and is classified as sensu stricto fibrosarcomas. However, knowing the symptoms and how tumors are diagnosed can help pet owners take action as soon as possible.


The early symptoms of feline fibrosarcomas may include swelling or tumors under the skin. These lumps may feel firm or hard to the touch and may not be painful for the cat. In some cases, these tumors may grow quickly, while in others, they may remain small for a long time. Panniculitis may also occur in the affected area. A ct scan can help diagnose the extent of the fibrosarcoma.

As fibrosarcomas, also known as tumors, can occur anywhere on a cat’s body, it is important to check your cat regularly for unusual lumps or bumps. This type of cancer is not only limited to cats but can also affect dogs. If you notice any suspicious growth, it is recommended to consult with a veterinarian who can perform diagnostic tests such as ed or biopsy.

Treatment options may include curietherapy, which involves using radiation to target the cancerous cells. It is also worth noting that fibrosarcomas can sometimes mimic other conditions, such as abscesses or cysts. So, if you are unsure about any lump you find on your pet’s body, it is always best to seek professional advice.


Diagnosis of feline fibrosarcomas, a type of tumor commonly found in cats, typically involves a biopsy or imaging tests such as X-rays or ultrasounds. A biopsy involves taking a small tissue sample from the lump and examining it under a microscope for signs of cancerous cells. Curietherapy, a type of radiation therapy, may also be used to treat feline fibrosarcomas. However, it is important to note that while fibrosarcomas are rare in dogs, they can still occur and require prompt veterinary attention.

Imaging tests such as X-rays or ultrasounds may also determine the extent of feline fibrosarcomas and whether tumors have spread to other body parts. Your veterinarian will likely recommend these tests if they suspect that your cat has a lump that could be fibrosarcoma. Curietherapy may also be an option for treating this type of cancer in cats.

In some cases, feline fibrosarcomas or tumors in cats may not show any symptoms until it has progressed to an advanced stage. This makes regular check-ups with your veterinarian all the more important, especially if your cat is older or at higher risk due to genetics or environmental factors.

Types and Causes of Fibrosarcomas in Cats

Fibrosarcoma is a type of cancer that affects the connective tissues in cats, resulting in tumors. It is an aggressive tumor that can spread to other body parts, making it difficult to treat. The causes of fibrosarcomas in cats are not fully understood, but et al. factors may play a role.

Three Types of Fibrosarcomas

Cats have three types of fibrosarcoma: injection site sarcoma, genetic mutation-induced sarcoma, and feline fibrosarcoma virus-induced sarcoma. All of these can lead to the development of tumors in cats.

The most common type of fibrosarcoma in cats is injection site sarcoma. This type develops at the site where a cat has received an injection or vaccine. Injection site sarcomas are typically slow-growing tumors that may not be detected until they have reached a significant size.

Genetic mutation-induced sarcomas, including fibrosarcoma tumors, occur when a mutation in one or more genes controls cell growth and division. These mutations can be inherited from a cat’s parents or occur spontaneously during cell division. One specific type of fibrosarcoma is oral fibrosarcoma, which develops in the mouth, while another type is site fibrosarcoma, which can develop throughout the body.

Feline fibrosarcoma virus-induced sarcoma is caused by a retrovirus known as feline leukemia (FeLV). This virus can cause tumors throughout a cat’s body, including on its skin and internal organs.

Causes of Fibrosarcomas

The exact cause of fibrosarcomas in cats is unknown, but several risk factors have been identified. These include tumors.

  • Age: According to et al., older cats are more likely to develop fibrosarcomas and other tumors than younger ones.
  • Breed: Certain breeds, such as Siamese, Himalayan, and domestic shorthair, are more prone to developing oral and site fibrosarcoma tumors.
  • Gender: Female cats are more prone to developing fibrosarcoma tumors at injection sites than males.
  • Vaccinations: While rare, some vaccines have been associated with an increased risk for injection site fibrosarcoma tumors.

In addition to these risk factors, radiation therapy has also been linked to cat fibrosarcomas development. Radiation therapy is commonly used to treat cancer in cats, but it can cause damage to healthy cells and tissues, leading to the formation of tumors.

Diagnosing Fibrosarcomas in Cats

Fibrosarcoma is a cancer affecting cats, specifically their soft tissues. A malignant tumor can grow and spread quickly, making early detection crucial for successful treatment. This article will discuss how vets diagnose tumors, such as fibrosarcomas, in cats.

Biopsy to Confirm Presence of Fibrosarcoma Tumors

The first step in diagnosing feline fibrosarcomas is to biopsy the affected area. This involves taking a small tissue sample from the tumor and examining it under a microscope to determine if it is indeed fibrosarcoma. The biopsy can be done using local or general anesthesia, depending on the size and location of the tumor.

CT Scans for Location and Size Identification

Once fibrosarcoma has been confirmed through biopsy, CT scans may be used to identify the location and size of strict fibrosarcomas. This aids in diagnosis as it helps veterinarians plan treatment options based on the tumors’ location.

Pathologist Examination Under Microscope

A pathologist can examine tissue planes and lymph nodes under a microscope to determine the extent of the tumors and whether they have spread beyond their initial site. Bloodwork and complete blood count can provide additional diagnostic information, such as anemia or changes in white blood cell counts.

It’s important to note that some cats with fibrohistiocytomas may not require aggressive treatment as these tumors tend to regress independently over time. However, due to their aggressive nature, other types, such as strict fibrosarcoma, require prompt intervention.

Treatment Options for Fibrosarcoma in Cats

Fibrosarcoma in cats is a type of cancer that affects the connective tissues. It is a challenging disease to treat, and the treatment options depend on various factors, such as the size and location of the tumor, its aggressiveness, and the cat’s overall health. This article will discuss some common treatment options for fibrosarcoma in cats.

Surgical Excision

Surgical excision is one of cats’ most common treatment options for fibrosarcoma. Surgical excision aims to remove as much of the tumor as possible while preserving healthy tissue. This procedure may involve removing a portion or all affected limbs if necessary.

The success rate of surgical excision for fibrosarcoma tumors depends on various factors, such as the size and location of the tumor. Still, it can be an effective option when performed early enough. After surgery, your cat may require additional treatments such as radiation therapy or chemotherapy to prevent recurrence at the site of fibrosarcoma.

Radiation Therapy

Radiation therapy involves using high-energy beams to destroy cancer cells. It can be used alone or with surgery to treat fibrosarcoma in cats. In addition, radiation therapy may be recommended if surgical excision is not possible due to the location or size of the tumor.

Radiation therapy for site fibrosarcoma can have side effects such as skin irritation and fatigue, but they are usually mild and temporary. Your veterinarian will work with you to manage any side effects your cat experiences during treatment.


Chemotherapy involves using drugs to kill cancer cells throughout your cat’s body. It can be used alone or with other treatments, such as surgery or radiation therapy. For example, chemotherapy may be recommended if your cat has an aggressive form of fibrosarcoma that has spread beyond its original location.

Chemotherapy can have side effects such as nausea, vomiting, diarrhea, and decreased appetite. Your veterinarian will work with you to manage any side effects your cat experiences during treatment.

Other Treatment Options

In addition to surgical excision, radiation therapy, and chemotherapy, other treatment options for cat fibrosarcoma may be available depending on the case. These options may include immunotherapy, cryotherapy, or electrochemotherapy.

Immunotherapy involves using the cat’s immune system to fight cancer cells. Cryotherapy involves freezing cancer cells with liquid nitrogen. Electrochemotherapy involves using electrical pulses to enhance the effectiveness of chemotherapy drugs.

Your veterinarian will work with you to determine the best treatment option for your cat based on their specific needs and circumstances.

Chemotherapy and Curietherapy for Fibrosarcoma in Cats

Chemotherapy and curietherapy are the most common treatments used to combat fibrosarcoma in cats. Both methods have proven to be effective, but each has its own set of advantages and disadvantages.


Chemotherapy is a treatment that involves the use of drugs to kill cancer cells. It can be administered orally or intravenously, depending on the drug used. Chemotherapy aims to destroy as many cancer cells as possible while minimizing damage to healthy cells.

One advantage of chemotherapy is that it can be used with other treatments, such as surgery or radiation therapy. This multimodal therapy approach has improved survival rates in cats with fibrosarcoma.

However, chemotherapy does have some drawbacks. One potential side effect is bone marrow suppression, leading to decreased white blood cell count and increased risk of infection. Other side effects may include nausea, vomiting, diarrhea, and loss of appetite.

Adjuvant Curietherapy

Adjuvant curietherapy involves using radiation therapy to kill any remaining cancer cells after surgical excision. This approach can help ensure that all cancerous tissue has been removed from the affected area.

Unlike chemotherapy, which targets cancer cells throughout the body, curietherapy focuses on a specific area. Unfortunately, this means that radiation exposure may also damage healthy tissue surrounding the tumor.

Despite this drawback, adjuvant curietherapy has significantly improved survival rates in cats with fibrosarcoma combined with surgery.

Feline Leukemia Virus

Feline leukemia virus (FeLV) is a retrovirus that can increase a cat’s risk for developing certain types of cancers, including fibrosarcoma. In addition, FeLV weakens a cat’s immune system making it more susceptible to infections and other diseases.

Cats that test positive for FeLV should be monitored closely for signs of fibrosarcoma. Early detection is key to successful treatment and may involve surgery, chemotherapy, and curietherapy.

Clean Margins

Surgical excision is often the first line of defense against fibrosarcoma in cats. The goal is to remove as much cancerous tissue as possible while leaving healthy tissue intact. This procedure is known as achieving “clean margins.”

Clean margins are important because they reduce the risk of cancer recurrence. If all cancerous tissue is not removed during surgery, adjuvant therapy such as curietherapy or chemotherapy may be necessary to eradicate cancer.

Vaccine-Associated Sarcoma and Treatment

Vaccine-associated sarcoma is a type of cancer that can develop in cats after receiving a vaccination injection. This cancer is rare, but knowing about it as a cat owner is still essential. The disease can be aggressive and challenging, so early detection and treatment are crucial.

Symptoms of Vaccine-Associated Sarcoma

It is important to keep an eye on your cat after they receive a vaccination injection. If you notice any swelling or lumps at the injection site that persists for over three months, it could be a sign of vaccine-associated sarcoma. Other symptoms include loss of appetite, lethargy, vomiting, weight loss, and changes in behavior.

Treatment for Vaccine-Associated Sarcoma

If your cat has been diagnosed with vaccine-associated sarcoma, the first step in treatment is usually surgical removal of the tumor. Surgery aims to remove the entire tumor and some surrounding tissue to ensure that all cancer cells have been removed.

After surgery, adjuvant radiotherapy or stereotactic radiation therapy may be recommended to target any remaining cancer cells not removed. Adjuvant radiotherapy involves delivering radiation directly to the affected area while sparing normal tissues as much as possible. Stereotactic radiation therapy delivers high doses of radiation precisely targeted at the tumor while minimizing exposure to healthy tissues.

Local disease relapses can occur despite treatment; additional treatment may be necessary to manage the tumor. Therefore, your veterinarian will monitor your cat closely for signs of recurrence and recommend further treatment.

How You Can Help

As a cat owner, there are several things you can do to help prevent vaccine-associated sarcoma:

  1. Please talk with your veterinarian about which vaccines are necessary for your cat based on their lifestyle and risk factors.
  2. Ask your veterinarian about alternative vaccination sites other than between the shoulder blades.
  3. Monitor your cat for any lumps or swelling at the injection site and report them to your veterinarian immediately.
  4. Follow your veterinarian’s recommendations for follow-up care after vaccination.

Prognosis and Survival Time for Cats with Fibrosarcoma

After discussing the symptoms, diagnosis, types, causes, and treatment options for fibrosarcoma in cats, it is important to consider the prognosis and survival time for affected felines.

Unfortunately, the prognosis for cats with fibrosarcoma is generally poor. Cancer often recurs and spreads to other body parts, even with aggressive treatment options such as surgery, chemotherapy, or curietherapy. The average survival time for cats diagnosed with fibrosarcoma ranges from 6-12 months.

However, it is important to note that every cat is different; some may respond better to treatment than others. Early detection and intervention can improve a cat’s chances of survival.

As a cat owner or caregiver, it is crucial to monitor your feline regularly for any signs of lumps or bumps that could potentially be cancerous. If you do notice anything suspicious, seek veterinary attention immediately.

In conclusion, while the prognosis for cats with fibrosarcoma may not be favorable overall, there are still steps you can take to give your furry friend the best chance possible. First, stay vigilant and proactive in monitoring their health and seek prompt medical attention.


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