Swelling under jaw

My 13 year old cat has some swelling under her chin. It's fairly minor and does not seem to bother her. She's eating and behaving normally. I have noticed a little bit of scratching, but nothing extreme. I probably wouldn't have even noticed it, but I noticed her skin showing through the fur on her chin and on the sides of her mouth a little bit. The swelling has not changed for the last week or so. Is this something I can just keep an eye on, or should I take her to the vet?

Hello!  You sound as if you'd really like me to say 'just keep an eye on it,' but I'm afraid that I don't have enough information here to rule out various worrying things.  You vet might want to rule out skin cancers, bacterial and yeast skin disease, abscesses, enlarged lymph nodes or deeper structures in the neck, dental disease, fungal disease and potentially endocrine diseases.   Any one of these could be quite mild to start with, but would potentially get worse over time.   Cats are masters at hiding pain; being solitary or colony animals (as opposed to living in cooperative units) they haven't benefited from evolving clear pain / illness signalling in the way that dogs have.  This means that cats can get quite poorly before they actually start to 'look' ill.  When it comes to cats, early prevention of escalation often proves to be key.

Thanks, that's helpful. I try not to be alarmist and run to the vet at every little irregularity, but definitely don't want to ignore potential problems. I'll make an appointment for her. Thank you!

Went to the vet this morning, she described the swelling as a "bulbous chin," and said it was just from chin acne. But she did see some dental issues that are probably causing some pain, leading her to rub her face on things,  leading to the acne. So she's scheduled for dental next week. I'm glad it's nothing serious and that I didn't wait to take her in. Thanks very much for your advice!