Can you really have SFN with a negative punch biopsy?
 

The only thing they saw were "occasional axonal swellings" on the lowest biopsy at the bottom of my leg. The neuro said that he has seen this happen, but I'm wondering. I see a new neuro very soon so I'm anxious to find out what he says. The soles of my feet have been SO BAD pain-wise the past few weeks---bright red, and swollen (just a bit swollen IMO but my husband says they look bad). It's so painful:( Thanks.

Sorry you are in so much pain. I used to have this too. I don't know the answer to this I'm afraid because mine were negative too but we're only taken from my upper calves - one on each side. I live in the Scotland/UK where testing for SFN is very rudimentary as far as I can see. So I have little faith in the punch biopsy results I had taken last year - especially because they had to be transported from my island home to the mainland.

My SFN has still been clinically diagnosed by a neurologist so I guess it must be possible to have it despite a negative punch biopsy - although none of my doctors seem terribly committed to finding out more I have to admit.

When the soles of my feet were very hot and swollen a few years ago, just as you describe, I was told by a podiatrist that my Rheumatoid Arthritis was flaring. But I actually think it may have been the SFN. Now my feet are mostly quite numb and the burning affects them less - but it affects my pelvis, hands and wrists and my gums more. My feeling is that this is because it's slowly killing off the tiny nerves in my toes and feet and progressing to other parts. This is depressing so I am constantly pushing to get the cause identified and acknowledged.

yes you can have SFN and still have a negative skin punch biopsy, if your degree of damage doesnt fit between the arbitrary 5-95% values. If your SFN is relatively recent and you dont have enough damage yet to equal the lower value it may well be classified as negative. If you have another skin punch biopsy down the road in time it may well be positive by then. the same holds true for long fiber neuropathy and Electromyography/ Nerve Conduction Studies.