GCA. biopsy

It is something to discuss with the rheumatologist - ask them if a positive/negative result will change anything they are going to do with regard to your treatment. To some extent it also depends on how long you are going to have to wait for a biopsy - and something you may not be able to influence: how experienced the surgeon is at doing TABs and how good the histologist is. Even when they are top notch, there may not be giant cells or signs of inflammation in the slides they look at.

That doesn't mean you don't have GCA - there are all sorts of reasons for a negative results including what are called skip lesions (not present evenly through the tissue), simply it isn't affecting the temporal artery but is affecting other arteries, you have already been on high dose steroids for too long and other factors. Diagnosing GCA is a clinical decision - unless the TAB is positive when that is 100% confirmation that it is GCA. But only about 40% are found to be positive. So even with a negative, your rheumy may ignore it because they are so convinced it is GCA and continue as they have started. If they will/are doing that - you do have a valid reason to ask if it is worth it. 

I had the TAB, although by the time I had it, it was far too late, as I'd been on pred for a long time and of course it came back negative.

But just to let you know that the procedure was painless, apart from the anaesthetic injections, which were a bit painful, but no more than the type you might have at the dentist.

The scar is under your hairline and I'm not even aware of it anymore.

I wish I had researched the biopsy for GCA more thoroughly.   I had one in Oct. 2016. The surgeon did not go into my hair line, even though he shaved my hair.  My biopsy was from the bottom to the top right in front of my ear.  1 1/2 - 2 inches.   When the results came back it describes the specimen as .5 cm and negative with scaring(the used another term but that is what my Rheumy said it meant).  She said it was a false positive but it was obvious that I had GCA.   So I was still treated the same as if it had been positive.  It is definitely something, knowing what I do now, I would discuss further with my Rheumy.

Hi, Gina:  I had a GCA scare shortly after I was diagnosed with PMR following an episode when my vision was distorted for about 15 minutes- not a typical symptom.  My rheumatologist thought it indicated GCA, my GP and eye doctor did not.

There are 3 possible outcomes of the biopsy:

(1) positive (you definitely have GCA),

(2) "false" negative (you have GCA but it was not detected), and

(3) negative and you don't have GCA.

If you fall in category (1), you know the worst and know you need to take prednisone and be very cautious in reductions.  If you are in category (3), you can reduce quickly to a PMR dose.

The problem, as you have learned, is that you can't tell the difference between results (2) and (3). With a negative biopsy, there is no way to exclude GCA. My biopsy was negative, and I found this frustrating and scary.  I reduced my prednisone quickly from 60 mg to 40 mg to 30mg to 25mg (in just over a week), then reduced more slowly.

However, I had a list of signs to look for and what to do if any occurred. For example, if I lost my vision, if I got to an emergency room and had a prednisone shot within an hour I MIGHT recover my sight. I found this pretty alarming.

I think there was a difference in my treatment based on the biopsy. If I'd had a positive result, I think I would have reduced more slowly.  My doctors and I would have been willing to take the risk of higher prednisone when we knew for sure that I faced the risk of sudden and irreversible blindness.

The procedure itself is minor. I had a local anesthetic and the doctor made a cut on the temple (in the hair) about an inch long and took samples of the wall of the blood vessel (which is just under the skin.)  

So definitely talk to your doctor about the practical outcome of the results of the test.  Best of luck!