Skin Biopsy for Neuropathy Question

Hello @elenal, Your profile mentions you idiopathic peripheral neuropathy since 2015. I've had neuropathy in my feet since my 50s and am now in my 80s. I was diagnosed with idiopathic small fiber peripheral neuropathy at Mayo Rochester in 2016 but they didn't do a skin punch biopsy as part of the testing. From what I've read they normally take a skin punch biopsy above the ankle and the upper leg for comparison. While you wait for members with experience to respond, I thought I would share this information that includes a video of the procedure that may explain it better. @cmartinjr, @artscaping, @boo55 and others may have some experience they can share with you.

--- Skin Biopsy, Cutaneous Innervation Laboratory - Neurology: https://www.urmc.rochester.edu/neurology/our-divisions/neuromuscular/neuropath/skinbiopsies.aspx

What other tests did you have done when you were diagnosed in 2015?

Hi there- I’m not sure why this is, but as with @johnbisjohnbishop, it’s my understanding that samples are taken above the ankle and in the upper leg. My symptoms are worst in my calves, and that’s still where the samples were taken. I think my doctor probably explained this to me, but it was so long ago I just can’t remember why.

The biopsy is considered non-invasive and usually only leaves a tiny scar, but one thing I needed to consider is if I really wanted to do it, as it doesn’t catch every case of small fiber neuropathy. At the time, my neurologist told me that it’s thought that perhaps even around 30% of cases lack a positive skin biopsy test (I’m not sure if that’s the exact number, but it was a sizeable percentage). It also wouldn’t have changed my treatment.

I did it anyway because I decided the potential for having more certainty and being able to confirm my diagnosis as small fiber neuropathy was important enough for me weighed against the drawbacks. In the end, it was still negative. One sample was “low normal” and the other was normal.

The biopsy location is standard - ankles. Some add two more areas higher up the leg to add the diagnosis of length-dependent vs non length- dependent. I never really thought about why the ankles are chosen specifically. But that is standard.

Hi my name is Caryn and I think I posted perhaps under the wrong question. I had a lot of information since I've had neuropathy for a long time and I did answer the question about the skin biopsy as well as other medications and other treatments so you can find me at c a r y n answering questions concerning neuropathy and also breast cancer. I hope it helps Good. Good luck with your search

The locations are chosen because that is where they have a large sample of data to be able to quantify normal vs abnormal results. It is great for length-dependent neuropathy, not so great for non-length-dependent.

So I was offered the skin biopsy and decided against it because my neurologist essentially said the same thing and that the treatment would be the same whether positive or negative.
What are your symptoms/treatment may I ask?

I would recommend doing the biopsy. After six years of searching, I felt such relief finally seeing on the report that I did actually have a reason for all the pain. No more skepticism from other medical practitioners. The biopsy is considered the “ gold standard” for definitive diagnosis.

That’s the same reason I did it, only I didn’t receive a definitive answer. For a “gold standard,” it has such a high margin for missing cases. So I can still see why someone wouldn’t want to do it for that reason. But I am glad you could see something concrete. All my conditions but one are clinical diagnoses—no objective data can capture it =(

Due to the unusual symptoms I was experiencing - from scalp to knees burning, itching, pins & needles, shocks, reddening, etc. , my neurologist (seeing for migraines) recommended the skin biopsies. They took samples from my left side - ankle, lower thigh, and my forearm. My ankle result was normal, but the other two nerve fiber densities were significantly decreased. Report states: Abnormal nerve fiber density at proximal sites with normal findings at distal sites. This pattern of findings suggests non length-dependent neuropathy affecting small nerve fibers. At least I know why my symptoms are occurring. However, still trying to determine the cause of the NLD-SFN. ANA positive points to an autoimmune disorder yet to be determined. Still doing various tests. Marilyn

Has anyone actually had some successful relief due to treatment?