@iceblue, I'll give it a try. This is a very complex and confusing subject.
The terms polyneuropathy, peripheral neuropathy, and neuropathy are often used interchangeably, but there is a difference. Polyneuropathy is more specific, and refers to a set of diseases characterized by multiple, often symmetrical nerve involvement. Peripheral neuropathy is more general, and can involve only one nerve, such as trigeminal neuralgia. Neuropathy is more general still, and can even mean involvement of the central nervous system.
Small fiber peripheral neuropathy is a form of polyneuropathy which refers specifically to the small fibers in the skin. This is the condition usually diagnosed with an epidermal nerve fiber density test (EFND), the "skin biopsy" often referred to here.
@burningfeetinphoenix, I don't quite understand your post about the podiatrist. If your skin biopsy was positive, then you do have small fiber peripheral neuropathy (SFPN). One way or another, I'd be careful about dealing with this podiatrist, as there is no evidence as yet that stem cells have a roll in treating any neuropathy.