I had the skin punch biopsy done a year ago, from the ankle and the upper thigh. Done at Therapath lab. It was negative. I also have full body burning, parasthesias, and itching. No official diagnosis, but Dr. suspects possible SFN. I have no loss of sensation anywhere and also have mild Erythromelalgia in feet and face. I've had all these sensations for 18 months. I still do not have my symptoms controlled with meds. My Dr. said it can't be CNS because I have normal MRI of head and neck.