Today my mom noticed a red lesion on my cat’s (Willow) armpit. We originally thought Willow was wounded from fighting with her older sister. Upon further inspection, we saw that she was not bleeding, but has this quarter-sized red raised mass under her arm. After treating my older cat, Pumpkin, for FIP earlier this year, I persistently researched the internet to learn that this may be cutaneous lymphoma. I am hoping that this is just a birthmark we never saw, but I’m getting scared. I will take her the vet tomorrow. She is only 1 year old. Is there any treatment for this? Any advice?
Firstly, I'd like to apologise for taking so long to get back to you - we're reviewing our protocol to make sure this doesn't happen again.
I certainly wouldn't jump to cutaneous lymphoma as a diagnosis. Whilst it's possible, it's relatively rare and the pictured lesion looks like any number of other, less serious, things. At such a young age, it's much more likely to be something else, so the odds are in your favour.
Unfortunately I can't say more about what it's likely to be without having a closer look and a good feel, but I'm hopeful this is something a lot more minor. I expect by now that you've seen the vet and had some treatment, but if there's anything else we can help you with please don't hesitate to ask.