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, it is usually in older cats.
Although harmless, in certain locations they can be a problem as they can press on other structures which can impede their function.
They can define as infiltrative or non-infiltrative.
- Infiltrative lipomas can invade surrounding muscle and connective tissue. Recurrence is quite common.
- Non-infiltrative lipomas remain within the fatty tissue only.
The cause of lipomas has not been established.
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.
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 if 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 evaluated 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 which can help your veterinarian determine the extent of an infiltrative tumour.
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.
Surgical removal if a non-infiltrative lipoma is impeding function.
Surgical removal of infiltrative lipomas with a wide margin. Radiation may be necessary as a follow up as it is often difficult to remove the entire tumour from surrounding tissue.
Recovery is straightforward with this surgery, however, keep your cat quiet for a few days during recovery.
Regularly heck cats from head to tow to look for lumps and if you do find something unusual, consult your 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.