Rocky has a Sarcoma

Rocky is our 13-year-old Bengal that my husband purchased from a breeder sometime in 2008. She didn’t come and live with me until 8 years ago, in 2013. In November of 2020 when I was out of town for a few days she got into a scuffle with one of our other cats. Rocky loves people, but doesn’t really like other cats. When I arrived home she had what appeared to be a ruptured abscess. I took her to the vet just to make sure it was indeed a ruptured abscess. We ran a basic senior blood panel as she was due for labs, and the vet checked her over. Everything checked out, the abscess started healing, and her labs were good. In January 2021 I noticed she developed a fatty, soft mass in the same area of her abscess. It wasn’t painful on palpation, and it wasn’t bothering her, so I just watched it assuming it was just inflammation or perhaps another abscess that would burst.

In February/March it was still there, so off to the vet we went again. This time my regular vet (who we did not see the first time) was immediately concerned and wanted to stick a needle in it. It didn’t drain any fluid, and she said it had a concerning pattern that didn’t look like an infection either. We sent out the cytology to pathology, which came back ‘maybe FISS (feline injection site sarcoma) or infection.’ Our only option for a real diagnosis was surgical biopsy, and I was extremely resistant to surgery. How could this be a sarcoma? She had an abscess from a fight, and she hasn’t been vaccinated at all since I’ve had her (at least 8 years). The only vaccination records I have on her are from 2013 when she was given a rabies vaccine, and rabies are generally given in the right leg, not the left. FeLV vaccines are given in the left rear leg, but I have no proof she ever received that vaccine, but I also have no proof that she didn’t.

In cats, sarcomas are almost always malignant, and most often associated with FISS. The treatment is radical amputation of the limb, and even with that, survival times are not great.

I pushed back hard on the idea that this could be a tumor. My vet could feel what she thought was a tumor, but I couldn’t rationalize how this could be a tumor, the series of events just didn’t add up. What made sense was this was an infection. We did a convenia injection, and at this point I decided to just watch it to see if it got bigger or smaller in the next few weeks. Unfortunately, in late March/early April things got a lot worse. She began to obsessively lick the mass, which then started to ulcer, and it became a huge swollen crusty mess. At this point we had no choice but to pursue surgery to debulk the mass and get a diagnosis. There was ‘something’ there during the surgery, but my vet didn’t know what it was. She said it didn’t look like a traditional sarcoma in a cat, but it also didn’t look like an infection. She removed as much of it as she could, but she left some, a lot, behind, because it extended into the muscle and she’s not a trained specialty surgeon. Histopathology confirmed that was a liposarcoma; a more common malignant tumor in dogs, but incredibly rare in cats. Because these tumors are so uncommon in cats, the pathologist had to use the sarcoma grading system for dogs to grade her sarcoma. It was originally graded a stage 2, but downgraded at her second surgery to a grade 1, meaning it has a low risk of metastasis.

Liposarcomas are incredibly rare in cats. I was only able to find one reported case in a 6 year old cat.

Liposarcomas are soft tissue sarcomas that are locally aggressive, meaning they rarely metastasize to other organs, but they attack the surrounding tissue and muscles. There are only “isolated reports” of liposarcomas in cats, and they are “most often found in the subcutis as a manifestation of injection site-associated sarcomas.” They are generally treated with surgery, marginally excursion whenever possible with wide margins to prevent regrowth. Chemotherapy is not often effective for these tumors, but sometimes radiation is. In dogs, soft tissue sarcomas have a good remission rate with wide margins, but the survival data is all over the place, with dogs living months to years. We had to wait six weeks for a consult with a board certified veterinary surgeon, during which her tumor grew back very quickly and was visible once again. After a CT scan, it was confirmed her tumor was rather extensive, extended not only into the muscle but up into her hip and was sitting on top of her sciatic nerve. The surgeon recommended aggressive surgery. Radical leg amputation with caudal hemipelvectomy, so removing part of her pelvis, too.

This was devastating news. Amputation is radical surgery. Removing a limb isn’t a choice one can make lightly.

As a Bengal Rocky loves to jump. Being high or on top of something is life for her. She eats on top of our stand up freezer, she spends all her free time sleeping on a chair or on a shelf or a cat tree. How could she jump or climb or run well with only three legs? I did a deep dive into tripod and three-legged cat/dog groups looking for Bengals that had done well with amputation. Many cats did well, even older cats, thriving on three legs, but the recovery was hard for many cats. Many had phantom nerve pain, and issues using the litter box as they adjusted to only one back leg. I was having a hard time rationalizing how fair it was to amputate on a 13-year-old cat. She’s a senior, although very healthy with no other underlining medical issues, it didn’t seem fair.

We opted for a second, aggressive debulking surgery knowing this wouldn’t be a cure, but hopeful it would delay regrowth much longer this time. The surgeon had to be incredibly aggressive in order to remove the entire tumor, taking the bulk of Rocky’s left leg muscles, and grafting some muscle over the top of her sciatic nerve to protect it from damage. While she was able to get the entire visible tumor, histopathology showed we did not get clean margins, meaning there is a strong possibility of regrowth. Sarcomas have ‘little tentacles’ as my surgeon called it, growing out beyond the actual tumor, which is why they recommend wide margins to prevent regrowth. This time the pathologist also said the tumor had some markings of being a fibrosarcoma, not just a liposarcoma, a stronger suggestion this is indeed a FISS. Although rare, FISS can appear up to 10 years after the vaccination, and the FeLV vaccine has known associations with sarcomas.

As I write this, Rocky is three months post-op and doing incredibly well. In fact, she’s doing much better than the surgeon anticipated after having so much muscle removed. She isn’t displaying any signs of pain or issues walking or jumping. She has some very minor weakness in the left leg when she has to lift it to step into something, like a litter box, otherwise it’s almost undetectable. For now, the goal is to try boost her immune system and prevent regrowth.