Lump on 5-month old kitty

[Mark]

Just discovered a kidney-bean-sized lump on my five-month old male cat, who is happy and healthy otherwise. It's on his right side by his rib cage. He lets me move the lump around and doesn't appear to be bothered by it. Obvious concern is the fibrosarcoma issue related to vaccines. He had all of his shots in the last couple of months, but does this area sound like a place they would inject a vaccine? What are some likely explanations for this lump and how concerned should I be? What should I expect the vet to do to make a diagnosis? Of course I will be taking the cat to my vet ASAP to have this checked out. Just curious in the meantime...

[Traci]

When was the LAST booster vaccination, and was it the FVRCP?

No, the side or above the rib-cage is not a typical area for vaccine injections, but rather over the right interscap shoulder, as forward as possible. If your vet gave the injection where you found the lump, this could be a localized reaction, but should be investigated by your vet immediately. Also inform him, IF the vaccination was given in that area, to get informed about the proper injection site locations of the body. Should a sarcoma develop where you say the lump is, there is no way to garantee complete excision and expect metastisis not to occur in that area, making any further attempts at removal difficult at best. This is why vaccines are given in a limb area, to spare life in the event an amputation is necessary due to a sarcoma.

It could also be a benign cyst, such as a sebaceous or lipoma, usually nothing to worry about, but in a 5-month old kitten, this would be uncommon. Get him checked right away, like tomorrow.

If your vet is not up-to-date on vaccination site locations, time to find a new vet.

[Gina]

Mark,

I hope you have your kitty at the vet by now, but just wanted to share that if he was ever an outside kitten, it could be a pellet or bb (from an evil evil cat hater). My poor Oscar had one embedded under his skin when I adopted him. Unbelievably, it didnt' seem to bother him at all. Once my vet took it out, I couldn't understand how! Just another possibility!

Let us know how it goes,
Gina

[Mark]

We're taking him to the vet tomorrow, so I will let you know what we find out. His first shots were in mid-May, then he got a booster or boosters in June and something else in early July when he was neutered. From what I've read, wouldn't it be too soon for a vaccine-related fibrosarcoma to develop?

[Traci]

To answer your question, when a lump doesn't disappear within thirty days of a vaccination, it's time to get it checked immediately. Usually, vaccines can cause mild reactions, such as tissue or muscle inflammation. But, they should reduce and disappear within 30 days. Never let it go further than that, ever.

[Mark]

I haven't let it go at all. I discovered the lump on Sunday.

I know I read somewhere that it takes at least three months for a vaccine-related fibrosarcoma to develop after the shot. Since Gus' first shot was in mid-May, wouldn't the timeline seem to rule out a tumor related to the vaccine? Not that it would rule out an old-fashioned tumor, of course...

[Traci]

Wherever you read that, you were misinformed, or the information was outdated. It was generally thought that a sarcoma was not evident until three months after an injection (keep in mind, this is the period in which owners didn't notice anything unusual until the tumor was obvious). However, there have been some sarcomas diagnosed and confirmed at or after 30 days post-vaccination (although they can be hard to differentiate at this early stage of tumor development). So, based on these findings and research, it is best to get any lump checked if it persists past 30 days, seems to suddenly occur, or changes rapidly in size, shape, form, location. This applies to ANY lump, not just a vaccine suspect lump.

As for other types of cancer growths, it would be uncommon for a 5-month old to develop a malignant tumor, but not to say it isn't possible, just simply rare. Simply due to his vaccination history and when you found the lump, is reason enough to get it fully evaluated. Don't want to alarm you, just want you to take precautions

[Mark]

Thanks for the reply, Traci. Dang, I didn't want to become an expert on sarcomas, and I hope tomorrow is the last I hear of it! And thanks Gina for your thoughts. It can't be a BB since he's never been outside for more than a few seconds. I wonder if this could be a swollen lymph node due to an infection? Now I'll have to do some research on the feline lymphatic system. I love the Internet. I'll keep you guys posted.

[Cleo]

Hi Mark,

Just wanted to wish you and Gus well at the vets tomorrow. Please post with an update as soon as you can.

Cleo

[Traci]

The area you describe doesn't sound like a lymph region......you can find the lymph nodes in the following areas: either side of the neck, just below the jawline; behind the front forelegs, where the chest wall meets the armpit; between the lower thighs.....the previous two are most common areas to enlarge due to an inflammatory response.

Again, we could be talking about a simple sebaceous cyst or lipoma. Another rule out might be an abcess or foreign body, or even a larvae (like cuterebra, a larvae/worm that is usually visible on the exterior, must be removed by your vet only). Let's hope for a simple problem that can be easily rectified/easily treated.

Do find out about the injection site locations, and ask the receptionist, tech or your vet if these were noted in kitten's health chart. Will watch for your update......hang in there.