I didn’t realise, at the time of posting, you had not yet had your chest X-ray.
At this point, it still sounds similar to what happened to me. I had raised ANCA (can’t remember if it was P or C, but they’re all associated with different types of vasculitis).
But inflammatory markers (CRP and ESR) were NOT raised - neither were any of the other tests abnormal. Raised ANCA in complete isolation is very unusual, and not diagnotistically very helpful. Although, to confuse things further, I’d had significantly raised ESR, reasons still unknown, when I’d visited the doctor a year or two before, for what I now think to have been a relapse.
I’ve had asthma and allergies all my life, but they are so common in the general population that I’ve never been convinced that has major significance, either.
Anyway, on discovery of the raised ANCA, I had both lung X-rays and kidney function tests. I was petrified of the lung X-ray, as my father (who had never smoked) had recently died of a rare form of lung cancer. As it was still very fresh in my mind, and I was feeling increasingly unwell, I’d half got it into my head I’d got the same thing, and was going to see a sinister mass there.
Anyway, lung and kidneys were both fine - which again was not typical of vasculitis, which would commonly affect one or both.
So they did the ANCA test again - NORMAL result. Whole thing immediately dropped, and never mentioned again. In fact, I’m not sure I was ever told, officially, I didn’t have vasculitis. But the focus immediately shifted back to MS, and I was fairly promptly diagnosed with that.
I’m still mystified by the abnormal ANCA and ESR readings (each just a single time). But from what I can gather, although ESR is variable, ANCA wouldn’t usually spontaneously correct itself.
I’m still curious whether they have bothered to retest you, as I only found out afterwards that it’s known for having quite a high rate of false positives.
Strictly speaking, an MS diagnosis is never 100% certain, unless arrived at post mortem, so I still occasionally wonder: “What if they were wrong, and these one-off anomalies DID mean something, and weren’t just laboratory quirks?”
But I think it all comes down to trust, in the end. My neuro is an MS specialist, and I have to trust he doesn’t just recklessly go around diagnosing people. Although he admitted diagnosis is never certain, he must have been certain enough for all practical purposes. It was enough to satisfy the insurers, and I feel they would quickly have seized on any doubts.
I don’t know what I’m trying to say, really. I suppose that your results, like mine, are “unexplained”, yet not typical of the raft of results you’d expect of someone who had any of the several forms of ANCA vasculitis.
I do think “Are you walking around?” is a pertinent question, because I remember thinking, when the same issue arose with me, that it seemed odd I wasn’t more ill. Of course, I was quite ill enough - it was MS, after all - but I’d had symptoms for years and years. All the evidence I could find suggested it was very unlikely I’d still be working, and walking around fine (well, nearly fine), if I’d had literally years of untreated CNS vasculitis. So that helped reassure me it couldn’t be it.
Oh, I forgot to tell you I’ve also had a skin rash, on my thigh - pinhead fine, but not raised. I was referred to Dermatology, but as there was a 12-week wait, there was nothing left for him to see, or biopsy, by the time I got there, so he issued me an open-ended re-appointment (so I wouldn’t have to go back through my doctor) and told me to ring if it happened again. Which it never has yet. So another thing on the list of unexplained happenings that don’t quite fit anywhere.
I still think you might end up back on the MS path, but perhaps with a few things that are never explained. One of the things that has stayed with me is my neuro telling me: “Common things are more common”. Whilst MS is still not exactly common, it’s far more so than ANCA vasculitis. So if it’s a choice between the two, probability lies on the side of MS.