I had my first Skin Punch Biopsy about 3 years ago, which confirmed SFN. I am having another one done tomorrow morning for the same reason you mentioned...curiosity. And my neuro agreed that it would be helpful by way of monitoring progression as well.

My first biopsy was taken at my right ankle and right hip. The hip was supposed to be the "control" to help determine how bad the ankle was. My pain was, and still is, mostly in my feet but both biopsies (ankle and hip) showed up as "abnormal" with very low small fiber nerve density.