Lipomas are slow-growing, benign (non-cancerous) tumours of the fat cells that are surrounded by a fibrous capsule. They are quite rare in cats and when they do occur, are mostly seen in older cats. They can develop on any part of the body, both inside and out, and they may be singular or multiple.
Although harmless, in certain locations they can be a problem as they can press on other structures, impeding function.
They can define as infiltrative or non-infiltrative.
- Infiltrative lipomas can invade surrounding muscle and connective tissue. Recurrence is quite common with this type of lipoma.
- Non-infiltrative lipomas remain within the fatty tissue only.
The cause of feline lipomas isn't known.
What are the symptoms of lipomas in cats?
Non-infiltrative lipomas are well defined, soft, round movable lumps under the skin. Cats with lipomas do not experience pain and there are generally no other symptoms present. They can range in size from a pea to several inches in diameter.
Infiltrative lipomas are typically less defined than non-infiltrative lipomas.
How are lipomas diagnosed?
Your veterinarian will perform a physical examination of your cat and obtain a medical history from you. He will need to run diagnostic tests to determine of the lump is a lipoma or a liposarcoma, which is a malignant growth of the fatty tissue.
Fine needle aspirate - A needle is inserted into the lump and aspirating a small sample. The contents are placed on a slide and checked under a microscope.
In some cases, a biopsy will be necessary if the results from the fine needle aspirate are inconclusive.
Ultrasound, x-ray or CT scans may also be required to determine the extent of an infiltrative tumour.
Blood work such as complete blood count and biochemical profile may be recommended, especially in older cats to evaluate overall health before surgery is carried out.
How are lipomas treated?
Your veterinarian may suggest a wait and see approach with a non-invasive lipoma depending on the size and location. If this is the case, it is important to regularly check it to determine if it is growing in size and impeding function.
If a non-infiltrative lipoma is impeding function, then it should be surgically removed.
Infiltrative lipomas will be surgically removed with a wide margin. Radiation therapy may also be required as it is often difficult to remove the entire tumour from surrounding tissue.
Recovery is relatively straight forward with this surgery, however, your cat should be kept quite for a few days while he heals.
All cats should be routinely checked over from head to toe to look for lumps and bumps. Anything unusual should be checked over by a veterinarian. Even though lipomas are generally harmless, it is impossible to differentiate without microscopic examination of the cells to differentiate between a benign and malignant lump. The earlier diagnosis is made, the better.