Injection site: Abscess? Sarcoma??

Hi all! I'm an American currently living in China, and I recently brought my male cat (maybe 10 months to a year old) to be neutered. The surgery was just under 2 weeks ago. Yesterday I noticed a separation in the hair on his neck, and then I saw what to me looked like an abscess somewhere in the scabbing phase. It doesn't feel raised, but it is hard like a scab and it seems to have an indentation with his fur still growing from the sunken middle. It's perfectly round and directly at the injection site-- here in China I don't really know what their vet practices are, but I watched him get an injection or 2 in this spot prior to the surgery. I assume it was a relaxer or something so they could shave and prep him.

I started looking into it and read about sarcomas, and now I'm really scared. Do they happen as a result of vaccines or the injections themselves? He didn't get any vaccines that I am aware of. I'm sorry my picture isn't better, but he won't let me get a clear one. I should say, it's not because it seems like it hurts him to have me touch it- he tries to play whenever I reach out to him. He seems to be eating, drinking and acting normally. I didn't take him back to the vet after the operation. He was supposed to go back a week after to have stitches removed, but he ripped his e-collar off and quickly ripped them out before I could get up and stop him. There was no bleeding or anything after the stitches came out, and he pretty much left it alone after that and it looks like surgery is healing up nicely.

What do you guys think? I've heard sarcomas can show up pretty soon after an injection but under 2 weeks seems really fast. I worry though because it doesn't look like a hole like most abscesses I've seen, and it's sunken in but I never saw any pus or any drainage. I never even saw a lump at all; i just saw the scab yesterday. What could it be?

Thanks in advance,
Kali

Quite a few years ago my cat did develop a lump not long after have an injection of flea medication in that spot. I did bring her to the vet right away and after examining her they suggested I wait and watch. It do go away on its own. It would probably be worth it to have the vet check it out.

Good luck!

Hi Kali,

Thanks for sharing. My cat has a spot at the site of an injection that looks just like the one you posted. I'm going to get an appointment with my vet as soon as possible, but I am really curious if it ended up being something serious with your cat or if it turned out to be no big deal. I hope it wasn't anything like the terrible stuff I'm reading on Google

Thanks!
-Eli