5 year old cat with acute limp/bone abnormality

About two months ago, my female cat began limping.  The vet's first suspicion was a sprain or arthritis.  
(She had been declawed by a previous owner and uses that paw to box the other cats and dogs, so a sprain was my first thought, too.)

The limp didn't improve and the following week she received a cortisone injection.  This had no visible effect, and two weeks later my vet took x-rays.  He said her humerus(?) (the upper arm attached at shoulder) -- and only that bone -- was mottled in a way that neither he nor his associates had previously seen.  (To me, it looked like someone had sprayed it with blotches uniformly across the surface.)  

He forwarded the x-rays to Purdue, and the radiologist called it a bone or calcium infarction and suggested that it might be secondary to an autoimmune or neoplastic condition.  We performed a blood chem panel and it was normal except for slightly low PHOS (2.4 mg/dL), WBC (4.32) and NEU (2.38) levels.

My vet offered to perform a full body scan on my cat but doubted that we'd find anything at this point, and I tend to agree.

A friend of a friend said that she'd had a cat with similar symptoms and x-rays and it was diagnosed as osteomyelitis.  However, my vet said that this does not have the appearance of osteomyelitis.

Throughout this period, her fur feels great, she's bright-eyed and has a healthy appetite.  I have had her for 4 years, and fed her only Wellness or Natura products.  (She will eat only dry food.)  Except for two outbreaks of (what I believe was) herpes, she has been very healthy. Despite her limp, she doesn't flinch when her arm is manipulated.  

The inference of cancer has greatly frightened me, and I am also concerned about the low phosphorus since it is related to bone development.

Has anyone encountered a similar condition?  I would be appreciative of any recommendations or suggestions that I could take back to my vet.

Thank you very much.

[zodiacqueen]

Hi, I have not dealt with this condition, but have you though of getting a biopsy?  I would be very surprised that your vet didn't already suggest this.

That's the only way that you'll be able to get a definitive diagnosis.  Ya can't be anymore accurate than that.

[2dogs3cats]

Thank you for your reply and suggestion.

My vet had not suggested a biopsy.  However, I just learned that there was more to the report.  (I think my vet was trying to protect me.)

My little one has been diagnosed with osteopetrosis, which is a rare and painful congenital disorder that is, effectively, untreatable and will shorten her life.  I am devastated.

[zodiacqueen]

Thanks for the update.  I am truly truly sorry that you did not get better news.  Maybe your vet will do his best to keep your baby as comfortable as possible-pain meds, phosphorous supplements.  And, I'd ask the vet straight up if he was trying to spare you.  That would, personally, p i s s me off.  Especially as much money as they get from me.  I'm sorry if that suggestion upsets ya, not sure if you're the type that likes to be spared or you're one that needs all the facts.  People go either way with that.

If it were me dealing with this diagnosis, I'd ask the vet if he was 100% positive of the osteopetrosis diagnosis.  If he was NOT totally sure, I'd ask for the biopsy.  That's the only ultimate proof you need that'll give you the 100% proof of what's truly wrong.  Since this is such a rare disease, maybe the vets are wrong in their guess.  To me without the biopsy, all the vets are doing is making guesses about your baby.  To me, that is not good enough.

I am sorry that you feel so stressed right now, but if this diagnosis is truly accurate, then I can definitely assure you that you'll be able to make your kitty more comfortable and keep her happy with symptom relief.

I'll keep watching this thread, if you need more advice or you want to gvie some updates.

PLEASE take care!!

Hugs
Staci