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Lipomas In Cats

Cats are known for their curiosity. However, if you come across a lump on your feline friend, you might be the one who becomes curious or even alarmed. While some level of concern is justified and an examination by a veterinarian is recommended, you should know that many lumps are harmless. One such type of lump that cats develop is called a lipoma. A simple lipoma is a fatty lump that forms under the cat’s skin. Lipomas in cats are not very common but they can form on various parts of the body, typically in cats 10 years of age or older. While a cat may have one or more lipomas, they do not spread, they tend to not grow very large and they are not painful. Furthermore, simple lipomas are benign and should not be confused with lymphoma, which is cancer of the lymph system. It’s worth noting that a cat need not be fat or overweight to develop a fatty tumor. No particular breed is more susceptible than others, and both males and females can develop a lipoma.

A simple feline lipoma typically can be surgically removed if they are not allowed to get too big or are not in an area in which it is difficult to do surgery. Since these fatty tumors can keep growing, some cat parents opt for removal whether it’s for cosmetic reasons or to prevent a tumor from affecting the cat’s quality of life. An example of the latter would be a cat having difficulty walking and/or jumping if a lipoma on its leg or abdomen grows big enough. Fortunately, the removal of lipomas in cats is typically curative. Removal does not rule out the possibility of another fatty tumor developing elsewhere, however.

Other Types of Fatty Tumors in Cats

Not all fatty lumps on cats are simple lipomas, and that’s why a veterinary exam is merited if you discover one. One type of lipoma is more invasive. There is also a type of cancer that originates within fatty tissue. 

Infiltrative lipoma: Unlike a simple lipoma, which is somewhat like a pouch, an infiltrative lipoma is a fatty tumor that invades into and around other types of tissue locally, such as between fascial plans and into muscle tissue.

Liposarcoma: A liposarcoma is a malignant transformation of fat tissue. Liposarcomas can be aggressive and can metastasize (spread) to the regional lymph nodes and lungs.

Clinical Signs to Look for

A fatty tumor can feel soft and squishy, like a water balloon beneath the cat’s skin. However, other tumors, both benign and malignant, can feel the same way. Fatty tumors that have grown big enough can be detected visually, but you or your veterinarian also may discover one while petting your cat or feeling for lumps as a regular precautionary measure. A lipoma in a less obvious spot might reveal itself in another manner. For instance, if a tumor is growing in the axillary area (the equivalent of an armpit), it might impact a cat’s range of motion to the extent that he or she limps or is unable to jump as gracefully as usual.

Workup and Diagnosis

Almost all lipomas appear on a cat’s outer body. Thus, a veterinarian might initially suspect that a lump is a lipoma based simply on its appearance and feel. To determine for certain whether the tumor is benign, a fine needle aspiration would be ordered.  For this test, the veterinarian would draw a sample from the lump to have it tested.

If surgery is indicated, further testing will be performed to determine whether the cat is healthy enough to handle anesthesia and the procedure. This is the case even for a benign tumor. Typically included in this workup are many standard tests: bloodwork, including a complete blood count (CBC) and blood chemistry profile; a urinalysis; and chest X-rays, to make sure the cat’s heart is not enlarged, which could add risk to the surgery.

Treatment Options and Prognosis

Fatty tumors in cats can be small or medium but don’t typically get very large. Since they can be diagnosed as harmless or cancerous, treatment options vary widely. Treatments include surgical removal, radiation, a combination or a wait-and-watch approach.

Surgery: Typical lipomas can be removed via a fairly routine surgical procedure. They usually come out in one piece and do not regrow. However, removal can be more complicated if the tumor is in certain locations. A mass is in the axillary area of a cat’s front leg can present a challenge, for instance, because important anatomical structures are there. The removal of infiltrative tumors is likewise challenging. They tend to intertwine with other tissues and do not shell out in one piece. The result is that surgery is not typically curative for infiltrative tumors. With a liposarcoma, removal is ideally achieved with wide margins of 3 centimeters — meaning no cancer is detected within 3 centimeters of the edge of the tissue that is removed. That can be difficult to achieve, however, and thus follow-up radiation treatment might be indicated.

Radiation: Surgery is not always an option, perhaps due to a cat’s overall health or a pet parent’s hesitance to put the cat through such a procedure. In those instances, as well as when a tumor is only partially removed or margins are not clean (wide) enough, radiation is an additional option. There are two types of radiation: conventionally fractionated radiation therapy (CFRT) and Stereotactic Radiation, both of which are designed to damage tumors without harming surrounding tissue or organs. The significant difference is that Stereotactic Radiation uses a higher dose of radiation. It is delivered directly to the tumor with an unprecedented level of accuracy, thus requiring one to three radiation sessions vs. the 15 to 21 that are needed with traditional CFRT. Since radiation requires a cat to be anesthetized, Stereotactic Radiation is also beneficial in terms of fewer anesthetic episodes. The team at PetCure Oncology has extensive experience providing this innovative treatment. Radiation can greatly impede or even stop the growth of infiltrating lipomas and liposarcoma tumors but is not typically completely curative. Depending on the cancer’s aggressiveness, a tumor might come back in six months or it could return in a couple of years. If tumors do begin to grow again, a cat can undergo an additional round of radiation assuming there is no metastasis.

Combination Therapy: If your cat’s tumor is diagnosed as a liposarcoma, your veterinarian may recommend a combination of surgery, radiation therapy and possibly chemotherapy. The exact course of action depends on the extent of the cancer’s growth and its level of aggressiveness.

Delayed treatment or no treatment: If your cat has a slow-growing lipoma that is on the smaller side, you and your veterinarian might adopt a watch-and-wait philosophy. Many fatty tumors only grow to a certain size and then remain in a quiescent phase, causing no problems. Conversely, fatty tumors left untreated can sometimes continue to grow and eventually become too large to remove. A liposarcoma left untreated can continue to grow and metastasize. Under those circumstances, a cat might begin to lose weight despite a normal appetite, as the cancer cells compete for nutrients. Eventually, the cat’s appetite will be suppressed because he or she doesn’t feel well, and lethargy may set in. At that point, decisions would have to be made based on the cat’s quality of life.

Find a PetCure Oncology Location Near You

PetCure Oncology treats lipomas in cats, as well as many types of cancer. Our mission is to give your cat the best quality of life and longest life possible. You will find that we are compassionate, supportive and professional throughout treatment and beyond. For more information about PetCure Oncology and our treatment options, find a location near you today.

More than 6,000 pet families have chosen PetCure Oncology for their dog or cat's cancer therapy. We give your pet a fighting chance to improve their quality of life. We understand. We commit. We will help.

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