Autoinflammatory vs autoimmune?

According to Claude AI app...
Yes, that's a fair and accurate characterization.
PMR is classified as an inflammatory rheumatic disease, but it doesn't fit neatly into either classic category:
Not clearly autoimmune: It lacks the specific autoantibodies that define classic autoimmune diseases (like rheumatoid factor or anti-CCP in rheumatoid arthritis). No consistent autoantigen has been identified.
Autoinflammatory features: PMR shows strong involvement of the innate immune system — elevated inflammatory cytokines (especially IL-6), a robust acute-phase response (high ESR/CRP), and a good response to glucocorticoids, all of which look more "autoinflammatory" than autoimmune.
But not purely autoinflammatory either: Unlike monogenic autoinflammatory syndromes (e.g., familial Mediterranean fever), PMR doesn't have a clear genetic mutation in innate immune pathways, and there's some evidence of adaptive immune (T-cell) involvement too.
So most current rheumatology literature describes PMR as occupying an intermediate or overlapping space — an immune-mediated inflammatory condition with a predominantly innate/cytokine-driven profile, without the autoantibody signature of classic autoimmune disease. It's also closely linked to giant cell arteritis, which shares this same ambiguous classification.

First, if you are going to quote something you found on the internet, please share the source with your audience. Without the source it is a guessing game on the reliability and applicability of the information. Your material sounds valid - however all information needs to be understood in context to be fully understood for applicability.
It is important to remember at all times that PMR is a default Dx. This means if it is not other things they test for then they default to PMR if you have certain symptoms and respond well to steroids. There is no definitive test to prove you have PMR. That being true it is impossible to say that PMR is a single medical problem. It could be a compound problem that needs to be peeled apart and treated individually. Even complicating it more - your version of PMR and my version of PMR may have similar characteristics but may not have the same root cause and thus may respond to identical treatments differently. PMR is complex mainly because it is not well understood.

There actually is a definitive test for both PMR and GCA (Giant Cell Arterits). It's called "Color Doppler Ultrasound," "Doppler Power Ultrasound," or "Musculoskeletal Ultrasound." They use it on your shoulders for PMR, and your head/temples and other spots to check for GCA.
They can see if there is fluid in the subacromial Bursa and other indicators of PMR in the shoulders.
I'm not sure what they look for to confirm GCA, but I got checked for GCA at same time as shoulders for PMR.
It's different from a standard Ultrasound machine from what I understand.
I'm not sure if they're easy to get in rural areas, but hopefully should be in many areas. It gave me definitive answers re having PMR and not having GCA.
Hope this information will help anyone who would like a definitive test.
Only wish none of us needed or wanted confirmation!!
Blessings to all of us

Just added 9/8/26:
Also, recently saw something re PET scans for confirming PMR.
https://www.sciencedirect.com/science/article/pii/S0001299826000772
I saw other links as well. It seems hopeful more awareness and methods of confirming PMR may be coming.
Wish no one needed them.
Blessings.

@jabrown0407
First of all, yes you are right in saying I should have provided sources. There were so many and so complicated/extensive . I am a bit of a newbie to this type of social media posting... so I hesitated to include. them.

secondly as later posts suggest there is beginning to be some types of tests that can indicate PMR more clearly. But yes, they appear to be not readily available and among Family physicians it is considered to be a diagnosis of exclusion.

It is a Dx of exclusion among Rheumy's as well. They have imaging tests but those are not conclusive by any means. They tried to tell me the pain in my right shoulder was PMR. I told them it was a pressure pain like something was pushing on my joint. My shoulder surgeon aspirated 3 vials of inflammation (yellowish liquid) from that shoulder. Pain gone! Nothing could be seen in the imaging in my left shoulder and no pain there either.
Until they find the cause they cannot develop a test and without a test it is a default Dx.

@judithgrossman

I appreciate the information you have shared and your contribution to this forum. I had a vague understanding of autoimmune vs. autoinflammatory, Now my comprehension is somewhat clearer.

The diagnostic default for PMR is the medical community saying, "We don't know what the problem is but since it responds to prednisone we will call it PMR."

I have been diagnosed with multiple autoimmune conditions. If you ask me... it doesn't matter what was diagnosed because everything hurt. PMR only added more pain to what was already painful.

I wish they didn't throw so much prednisone at all of my problems for 30 years. In my case, the better solution would have been a test for my IL-6 level and stop the pro-inflammatory effects of that cytokine!

I think people diagnosed with PMR are on the spectrum. In the case of PMR, it is somewhere on the spectrum of inflammatory conditions.
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I like the criteria to classify PMR from back in 2012. Not that much has changed since then.
https://pubmed.ncbi.nlm.nih.gov/22388996/
I especially like the last sentence of this abstract.

"These criteria are not meant for diagnostic purposes."

@boomermeg
According to the Claude app...
Mostly true, with one important caveat: it's accurate for GCA, but "definitive" overstates things for both.
For GCA: Ultrasound is now integral to the 2022 ACR/EULAR classification criteria for GCA, and temporal and axillary artery ultrasound is recommended as the first-line imaging technique to check for mural inflammatory changes in patients with suspected GCA. Evidence has shown color duplex ultrasound (CDUS) is more sensitive, less invasive, faster, and less expensive than temporal artery biopsy, which used to be the gold standard. So yes — ultrasound of the temporal arteries (and other cranial/large vessels) is now a well-established, guideline-endorsed way to confirm GCA, often replacing biopsy. (Diagnosing vasculitis with ultrasound: findings and pitfalls - Wolfgang A. Schmidt, Valentin S. Schäfer, 2024 +2)
But "definitive" isn't quite right. Diagnosis is typically made by combining a clinical pretest probability assessment with the ultrasound result — it's not a standalone yes/no test. It's also operator-dependent: the main limitation is that reliability depends on the technical expertise of the ultrasonographer. So it's the preferred first-line confirmatory test, not an infallible one. (Rheumatology Advisor) (nih)
For PMR: this is where the claim is weaker. Diagnosis of PMR rests on clinical signs and symptoms — there's no equivalent classification criteria that treats ultrasound as confirmatory the way GCA's does. Ultrasound can show findings like subacromial bursitis, biceps tenosynovitis, or glenohumeral synovitis that support a PMR diagnosis and help distinguish it from other conditions (like RA), but it's a supportive tool, not a definitive test — PMR remains largely a clinical diagnosis of exclusion, often made retrospectively based on response to steroids. (Rheumnow)
So: solid confirmatory role for GCA, useful supporting role (not definitive) for PMR.

@kjoed53
Thanks for all of that information from Claude. It's helpful to get information from different sources.
I was fortunate to have my Ultrasound done by an older MD with FACR and RhMSUS training and many years of experience.
You are correct that it depends a lot on the technician operating the Ultrasound and their education, experience, etc.
I've noticed that much of the information returned from queries will differ at least to some degree depending upon which search engine or App I'm using. Even the same search engine, when querried on laptop compared to smartphone has been slightly different. At any rate, I've found information that states that Ultrasound is used as first line practical tool due to it's price, and availability, and has 93-99% accuracy/specificity to detect bilateral subacromial-subdeltoid bursitis and PMR related activity.
I'm not sure if you saw another comment I made that PET is being used to diagnose more complex cases where whole body scan is needed to investigate for PMR and can detect GCA. It's not commonly used due to radiation, cost etc., but is also available. It's 18F-FDG-PET/CT specifically.
So, there are different scanning tools being used with different degrees of accuracy/specificity, and Ultrasound is 93-99% accurate to diagnose PMR in shoulders specifically. GCA can be detected also by Ultrasound. For whatever it's worth to anyone who'd like to look into Ultrasound as a pretty accurate tool. I hope all of the information we find and share is helpful to someone. Blessings.

@boomermeg

I get worried about some of the artificial intelligence information that is generated. The source of the information is sometimes attributed to online patient forums. There is one PMR forum where the same information is repeated over and over again about the "best way" to taper off prednsone. There is no medical research that explicitly states that one method of tapering off Prednisone is superior to any other method. However, artificial intelligence cites a patient forum as the source of the information as if it is a fact.
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At least the AI search I did on the above paragraph admits to a flaw.

" If an online patient forum repeats a specific, highly detailed Polymyalgia Rheumatica (PMR) tapering schedule thousands of times, the AI learns that this pattern is highly relevant to the topic. Without strict guardrails, the AI can mistakenly echo that community consensus as if it were a proven medical fact."