Can A Lipoma Become Cancerous In Cats?

What is a lipoma?

A lipoma is a benign (non-cancerous) fatty tumor that develops in the soft tissues of cats, typically between their skin and muscle layer (Mayo Clinic, 2022). Lipomas are very common in older cats, especially those over 8 years old. These tumors form as the fat cells proliferate and clump together into a soft, movable lump under the skin. Lipomas are usually oval or round in shape and have defined edges. They often feel rubbery or spongy and can range in size from very small lumps to large masses over 4 inches across. While a lipoma can develop anywhere on a cat’s body, common locations include the abdomen, chest, legs, and shoulders.

Lipomas themselves are harmless, painless, and do not typically impair a cat’s movement or quality of life (Cleveland Clinic, 2020). However, their appearance and tendency to grow over time can be concerning for cat owners. Most veterinarians can diagnose a lipoma simply by feeling and examining the lump.

Are lipomas dangerous?

Lipomas are almost always benign (noncancerous) and harmless tumors that form from fat cells [1]. While they can develop anywhere on the body where fat tissue is present, they are not considered dangerous in most cases.

In rare instances, an abdominal lipoma can grow large enough to cause discomfort or pain by pressing on internal organs. A lipoma around joints or tendons could also potentially limit mobility if allowed to grow unchecked [2]. However, as long as the lipoma is monitored and properly treated, these risks are low.

Overall, lipomas tend to be slow-growing and are benign, so there is minimal risk involved. The exception would be if the lipoma interferes with normal body functions, in which case a veterinarian should evaluate treatment options.

Can a lipoma turn into cancer?

It is extremely rare for a lipoma to transform into cancer. Lipomas are benign tumors composed of fat cells, while cancers are malignant tumors that can invade and destroy surrounding tissue. According to one study, the rate of malignant transformation is estimated to be around 0.003% to 0.02% (1).

In very rare cases, a lipoma can transform into a liposarcoma, which is a type of cancer that develops in fat cells. Liposarcomas are classified into several subtypes, including myxoid liposarcoma, pleomorphic liposarcoma, and dedifferentiated liposarcoma. Myxoid liposarcomas account for about 50% of all liposarcomas (2).

Some key differences between lipomas and liposarcomas are that liposarcomas tend to grow rapidly, may feel firm or painful, and can spread to other areas of the body. In contrast, lipomas usually grow slowly, feel soft and doughy, and remain in one area (3).

While the chances of a lipoma becoming cancerous are extremely low, it’s recommended to have any lumps or growths evaluated by a veterinarian, especially if they display any unusual features or changes.





What causes a lipoma?

There is no definite cause identified for why lipomas develop in cats. However, there are some potential factors that may increase the risk of a cat developing these fatty tumors:

Genetics may play a role, as some cat breeds like Domestic Shorthairs seem more prone to lipomas than other breeds (Source). The tendency to develop lipomas may be inherited.

Diet and obesity are also believed to contribute to lipoma development. Overweight and obese cats are more likely to get lipomas than cats fed an appropriate diet and weight (Source). Excess fat cells may multiply abnormally and form lipomas.

While the exact triggers are unknown, genetics and obesity seem to be risk factors. Monitoring your cat’s weight and feeding species-appropriate diets may help reduce the chances of developing fatty tumors.

Diagnosing a lipoma

To diagnose a lipoma in cats, the veterinarian will first perform a physical exam and observe the lump. They will look for key characteristics of a lipoma, like a soft, movable mass under the skin. The vet will take note of the tumor’s location, size, shape, and feel. Lipomas are usually round or oval shaped and feel squishy or rubbery. They move freely under the surface of the skin and are generally not attached to underlying tissues.

The vet may use a needle to extract cells from the lump in a process called fine needle aspiration. They will examine the cells under a microscope which can help rule out cancer. According to PetMD, “Lipomas have a very uniform appearance microscopically. They are composed entirely of fat cells.”

If there is any suspicion of malignancy, the vet may recommend a biopsy to examine a small piece of the tumor. This allows them to make a definitive diagnosis. As VRA Veterinary Care states, “We recommend biopsy of any rapidly growing mass to ensure it is not malignant.”

Treatment options

There are a few options for treating lipomas in cats:

Observation is often the first approach if the lipoma is small and not causing any problems for the cat. Since most lipomas are benign, many vets recommend monitoring the lump at home unless it starts to impair mobility or quality of life.

Steroid injections can sometimes be used to shrink the lipoma if it is in an awkward location or growing rapidly. Steroids help reduce inflammation and may cause the lump to decrease in size temporarily.

Surgery is usually reserved for lipomas that are large, impairing mobility, growing quickly, or if there is a suspicion of malignancy. Surgical removal completely eliminates the lipoma and can provide a biopsy sample to test for cancer. According to, surgery for feline lipomas typically has a good prognosis, but depends on the location and whether the mass can be fully excised.

Discuss all treatment options with your veterinarian to determine the best approach for an individual cat and their specific lipoma.

Preventing lipomas

There is no definitive way to prevent lipomas from developing in cats. However, there are some steps cat owners can take that may help reduce the risk:

Maintaining a healthy weight – Overweight and obese cats are more prone to developing lipomas. Keeping your cat at an optimal weight can help prevent obesity-associated health issues like lipomas. Feed an appropriate diet for your cat’s age and activity level.

Providing an enriching environment – Lack of exercise and mental stimulation may contribute to lipoma development. Make sure your cat has opportunities for daily play and activity. Provide interactive toys, cat trees/perches, and spend time playing with your cat each day. This helps prevent obesity and relieves stress.

While no prevention method is foolproof, keeping your cat active, mentally engaged, and at a healthy weight gives them their best chance at avoiding lipomas. Check with your veterinarian if you have any concerns about your cat’s weight or health.


The prognosis for cats with benign lipomas is generally excellent. Lipomas themselves are harmless, noncancerous fatty masses that usually do not impact a cat’s health or quality of life. As long as the lipoma does not grow extensively or interfere with movement, most veterinarians will recommend leaving it alone.

However, since lipomas can potentially become cancerous, regular vet checkups are recommended to monitor the size and texture of existing lipomas. If a lipoma starts growing rapidly, feels hard or fixed to underlying tissues, or becomes ulcerated or inflamed, further testing like a biopsy may be required to check for signs of cancer.

Warning signs that a lipoma may be transitioning into a malignancy include:

  • Rapid enlargement
  • Development of surface ulceration
  • Pain or inflammation
  • Loss of mobility due to size/location

If caught early while still small and localized, the prognosis for malignant liposarcomas can be good with surgery. However, liposarcomas have a high rate of recurrence and can spread to other body parts, negatively impacting prognosis. That’s why monitoring benign lipomas for any suspicious changes is important.

With regular vet care and monitoring, most cats can live happily with benign lipomas. But any growths exhibiting warning signs should prompt veterinary advice to determine appropriate next steps.

When to see a vet

If your cat develops a new lipoma, it’s a good idea to have your veterinarian examine it to confirm that it is benign. However, in most cases, lipomas in cats do not require any treatment unless they are causing problems.

You should take your cat to the vet if you notice any of the following signs with an existing lipoma:

  • Rapid growth – A lipoma that suddenly starts increasing in size may be a sign of cancer and should be evaluated.
  • Impairing mobility or organ function – Lipomas in areas like the armpit or groin can restrict movement or put pressure on internal organs. These may require surgical removal.
  • Ulceration or bleeding – This can be a sign of malignancy and warrants further diagnostics like a biopsy.
  • Suspected malignancy – If the lipoma feels firm or fixed rather than soft and mobile, it could potentially be cancerous.

In addition to monitoring existing lipomas for any troublesome changes, you should also have any new lumps or masses examined by your vet to determine if they are benign lipomas or potentially something more serious. Catching cancer early greatly improves the chances of successful treatment.

Don’t hesitate to bring your cat in if you have any concerns about changes you notice in a lipoma. It’s better to have it checked and find out it’s nothing serious rather than waiting until later. Your vet can recommend the best course of action if the lipoma does turn out to need intervention.

Lipoma FAQs

Here are some common questions about lipomas in cats:

Are lipomas in cats cancerous? rare, it is possible for a lipoma to develop into a liposarcoma, which is a type of cancerous tumor. However, most lipomas are benign fatty tumors that do not turn cancerous. Your vet can help determine if your cat’s lipoma is cancerous through testing.

How can I tell if my cat has a lipoma? Lipomas usually feel soft and movable under the skin. They are often round or oval shaped lumps that do not cause pain or other issues for the cat. However, it’s important to have any new lumps or bumps checked by your veterinarian to confirm it is a benign lipoma.

Scroll to Top