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Neurofilament Stain

Jon Wilson, MD neuropathologist at arkana laboratories
By Jon Wilson, MD

Aug 19, 2022

Small Unmyelinated Fibers Seen In Neurofilament Stain

This 35-year-old patient presented with complaints of numbness and tingling involving their feet, and distal lower extremity muscle weakness. Electrodiagnostic studies showed features of a sensorimotor axonopathic process. A sural nerve biopsy was performed.


Neurofilament immunohistochemical stain highlights axons in the sural nerve tissue sections. The small somewhat clustered structures highlighted by this stain represent which of the following?


A. Schwann cells

B. Small myelinated fibers

C. Large myelinated fibers

D. Small unmyelinated fibers



Correct answer: Small unmyelinated fibers

The neurofilament stained structure arranged in small clusters represent small diameter unmyelinated axons.


Reference(s) / additional reading:


Arcilla CK, Tadi P. Neuroanatomy, Unmyelinated Nerve Fibers. [Updated 2022 Jan 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from:

Harty BL, Monk KR. Unwrapping the unappreciated: recent progress in Remak Schwann cell biology. Curr Opin Neurobiol. 2017 Dec;47:131-137. doi: 10.1016/j.conb.2017.10.003. Epub 2017 Nov 6. PMID: 29096241; PMCID: PMC5963510.

Ioghen, O., Manole, E., Gherghiceanu, M., Popescu, B. O. , & Ceafalan, L. C. (2020). Non-Myelinating Schwann Cells in Health and Disease. In S. J. Baloyannis, F. H. Rossi, & W. Liu (Eds.), Demyelination Disorders. IntechOpen.

Nathani D, Spies J, Barnett MH, Pollard J, Wang MX, Sommer C, Kiernan MC. Nerve biopsy: Current indications and decision tools. Muscle Nerve. 2021 Aug;64(2):125-139. doi: 10.1002/mus.27201. Epub 2021 Feb 25. PMID: 33629393; PMCID: PMC8359441.


Quick note: This post is to be used for informational purposes only and does not constitute medical or health advice. Each person should consult their own doctor with respect to matters referenced. Arkana Laboratories assumes no liability for actions taken in reliance upon the information contained herein.