Maybe ingrown fur?

Question
A little while ago I noticed a small bump on my cats chest. It doesn't seem sensitive at all, she doesn't seem to react when it is touched. I'm not sure if cats can even get ingrown hairs, but it looks like that might be what it is. There is a small hole in the skin directly above the lump, and 'inside' it looks grey, as if it might be fur in there.
Does this sound like ingrown fur, or something else? If it is fur, how would this be treated at home?
Thanks!

Answer
Hi Sarah,

It sounds possible that what you've discovered is a sebaceous cyst. They derive their name from the fact that they are filed with an oily substance called sebum, which is typically white to gray in color. The cysts are common, with some cats more predisposed. While they don't always have a known cause, small injuries like scratches, splinters, and, yes, ingrown hairs, are some known causes. Fortunately, the growths are benign and usually need no treatment at all.

Most sebaceous cysts are slow-growing. Unless in a critical location, they don't interfere with normal function, and they don't cause pain. Some stay very small, and some continue to grow until they are about the size of a pea. At some point, they may burst like a pimple (and, in essence, they are very similar). If this occurs, you should gently squeeze out as much of the waxy substance as you can and rinse with a gentle soapy water (this isn't a dangerous job but can be dirty, so some prefer to bring the cat to the vet for cleanup). If the skin is open, apply a very thin layer of triple antibiotic ointment. The site may continue to drain for a short period, and it's likely that another cyst will arise later in the same spot.

Because of the propensity of these cysts to recur and even worsen in reaction to trauma, it's not recommended to try to remove or drain them surgically unless they become infected or are in a place where they are causing significant problems. It's truly best to just leave them alone.

All that said, cats can experience a number of lumps, ranging from abscesses to malignant tumors. I've gone into detail about the one that sounds most likely to me by your description, but you should have a vet properly diagnose her, and treat her, if necessary. Good luck!

Jessica