--a "neurite" is simply an axon or nerve fiber--the part of a nerve cell that extends from the cell body and conducts electrochemical messages.

The small-fiber nerves are mostly axon--many have their cell bodies far from the eventual sensory surface and the axons, while very thin, can extend for feet in length.

If it does say 189 per square millimeter of skin that actually sounds pretty high. I am not certain how that lab does its analysis, although the reference to seventeenth percentile does seem to indicate "within normal range" according to the McArthur protocols (though I think those rather arbitrarily were set to define below the fifth percentile or above the ninety-fifth percentile as "normal"). But, again, we don't know where you "started" in terms of nerve fiber density before this; seventeenth percentile may represent a dimunition for you, or it may not.

From my own skin biopsy results, the McArthur protocols list the following "normal" means and standard deviations, in fibers per square millimeter :

Thigh: 21.1 mean, 10.4 standard deviation

Distal leg (ankle) 13.8 mean, 5.6 Standard deviation

This means, going by a standard distribution, the fifth percentile for thigh is 5.2, and for distal leg (ankle) it's 3.8 (also listed on the report). My report (at least my first one) gave a nerve fiber density of 5.0 for thigh and 3.2 for distal leg (ankle) also indicated "excessive branching and swelling", consistent with a small-fiber neuropathy.