Fatty Skin Tumors in Cats

When a cat presents with lump or bump on the body, it should not be ignored. Veterinary diagnosis will be needed to distinguish benign lipomas from other similar masses that may be cancerous and likely to metastasize. Early diagnosis and treatment of cancer is critical to increasing the likelihood of a positive outcome. In the case of undiagnosed masses, it is always better to be safe than sorry.

Fatty tumors, also called lipomas, are soft, lumpy masses that move fairly easily under the surface of the skin. These benign masses are often relatively harmless and tend to grow slowly. A more concerning variation of the condition, known as infiltrative lipoma, occurs when the tumor grows into the surrounding muscles, blood vessels, cartilage, or collagen.

The primary symptom of fatty skin tumors is the presence of a mass directly under the skin that is well-defined and soft to the touch. The lumps tend be round or oval in shape. They are most commonly found on the abdomen, chest, or undercarriage of the cat, but may appear on any part of the body. In some cases, muscle swelling near the area may also occur.

The presence of fatty skin tumors has not been linked to any specific cause and is thought to be a result of the natural aging process. The condition is fairly rare in cats, and is most likely to be found in Siamese males that have been neutered. It has been determined that obesity is not connected with an increased likelihood of the development of fatty tumors.

Prior to examination, the veterinarian will review the cat’s full medical history and obtain details regarding the onset of symptoms, whether the mass has changed in size or shape, and whether the pet is exhibiting signs of discomfort. A complete physical exam will be performed and it is likely that a series of standard diagnostic tests will be ordered to rule out the presence of other medical conditions. Common tests include a complete blood count (CBC), electrolyte test, urinalysis, and thyroid test. An antibody test may be performed to check for the presence of infectious disease, and in some cases an EKG will be ordered to rule out underlying heart conditions.

All lumps will likely be aspirated with a fine needle to extract tissue samples for laboratory testing. The test is minimally invasive and sedation is not likely to be needed. In some cases, a biopsy will be performed under anesthesia. The purpose is to definitively determine whether the lump is benign or malignant. A CT scan or MRI may be needed to clearly visualize the mass and determine the extent to which it has extended into nearby tissue. This will help to develop a detailed surgical plan.

If the mass has been definitively diagnosed as a benign lipoma and it is not restricting movement or causing discomfort, the veterinarian is likely to recommend leaving it alone. If it is extremely large or is located in an area such as the lower chest or between the legs, it can affect the cat’s ability to move freely or decrease the overall quality of life. In this case, surgical removal will be recommended. Small masses that have not infiltrated into other areas are relatively easy to remove and the prognosis is very positive.

The removal of infiltrative lipomas may be much more complicated. If the mass has spread into the surrounding healthy fat or other tissue, it may be difficult to determine the outside borders. A larger area typically must be removed and the difficulty of complete removal make it more likely that the condition will recur. In some cases, radiation therapy will be recommended in addition to surgery to help improve the chances of success.

In cases where laboratory tests were not able to conclusively determine that the tumor is benign, surgical removal will be required. It is likely that the surgeon will remove both the tumor and a portion of the surrounding healthy tissue in order to increase the likelihood of a positive outcome.

Whether or not surgery has been performed, regular veterinary follow-up appointments are recommended. Following a surgical procedure, the vet will want to ensure that the cat is healing properly and monitor for possible complications.

If the mass has not been treated, ongoing monitoring will be needed. Any changes in the size or location of the mass warrants prompt veterinary examination. If additional masses appear on the cat, it should not be assumed that they will all be benign. Each instance should be individually examined and diagnosed by a veterinary professional.