History
41 year old female, 22 weeks pregnant, with onset of oral ulcers & motor sensory neuropathy during prior 8 weeks
Sural Nerve: Skip serial sections
Behçet Nerve Pathology
Varied loss of Axons among fascicles
Severely damaged fascicle with loss of axons & endoneurial cells (White Arrow)
![](../pics/biopsy/inflammation/behcet/behcetnvnfil2smar.jpg)
Neurofilament stain
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Behçet Nerve Pathology
Perineurial Damage (Yellow Arrows)
Lymphocytic inflammation around a small epineurial vessel (Black Arrow)
Vein &
Artery Damage (White Arrow)
Endoneurial Pallor (Blue Arrow)
![](../pics/biopsy/inflammation/behcet/behcetnvhevlpsmar.jpg)
H&E stain
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Behçet Nerve Pathology
Varied loss of Axons among fascicles
Severely damaged fascicle with loss of axons & endoneurial cells (White Arrow)
Perineurial Damage (Yellow Arrows)
![](../pics/biopsy/inflammation/behcet/behcetvvgvlp2ar.jpg)
VvG stain
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Behçet Nerve Pathology
Varied loss of Axons among fascicles
Severely damaged fascicle with loss of axons & endoneurial cells (White Arrow)
Perineurial Damage (Yellow Arrows)
![](../pics/biopsy/inflammation/behcet/behcetnvgtvlpsm2ar.jpg)
Gomori trichrome stain
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Behçet Nerve Pathology
Local Infarction: Varied loss of Non-myelinating Schwann cells among fascicles
![](../pics/biopsy/inflammation/behcet/behcetnvncamsm.jpg)
NCAM stain
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Vessel Pathology
Epineurial Veins: Damaged or Occluded
![](../pics/biopsy/inflammation/behcet/behcetyveinsvvgsm2.jpg)
VvG stain
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Epineurial Artery: Occluded
![](../pics/biopsy/inflammation/behcet/behcetoccart.jpg)
H&E and Neurofilament stain
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Lymphocyte Inflammation
![](../pics/biopsy/inflammation/behcet/behcetinfvess2sm.jpg)
H&E stain
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Inflammation
Associated with: small epineurial vessel
![](../pics/biopsy/inflammation/behcet/behcetinfvess1sm.jpg)
H&E stain
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Epineurial Neovascularization
![](../pics/biopsy/inflammation/behcet/behcetneovasculexlp.jpg)
UEA I stain
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Epineurium
Multiple, Small vessels
![](../pics/biopsy/inflammation/behcet/behcetneovasculexmp.jpg)
UEA I stain
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Epineurium
Multiple, Small vessels
MCH-I upregulation by Epineurial connective tissue
![](../pics/biopsy/inflammation/behcet/behcetmhc1.jpg)
MHC Class I stain
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Endoneurial Microvessels: Dilated
![](../pics/biopsy/inflammation/behcet/behcettblp.jpg)
Toluidine blue stain
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Endoneurial Microvessels
Size: Large
Lumen: Large; Filled with RBCs
Wall: Thin
Axons
Loss of large & small Myelinated axons
Remaining axons: Small
Wallerian degeneration: Scattered ovoids
![](../pics/biopsy/inflammation/behcet/behcettbhp.jpg)
Toluidine blue stain
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Behçet: Perineurial Pathology
![](../pics/biopsy/inflammation/behcet/behcetperineurthkvvglp2.jpg)
VvG stain
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Fascicles with Thick, Irregular Perineurium
Axon loss: Intrafascicular variation
![](../pics/biopsy/inflammation/behcet/behcetfascperineur.jpg)
VvG stain
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Fascicles with Non-uniform, Irregularly-stained Perineurium
![](../pics/biopsy/inflammation/behcet/behectperineurc5b9mpsm.jpg)
C5b-9 stain
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Wallerian Degeneration
![](../pics/biopsy/inflammation/behcet/behcetfascwd.jpg)
VvG stain
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Fascicles with Active Wallerian Degeneration
Pale, Irregularly-stained Myelin (Above; Arrow)
Acid phosphatase stains a few degenerating myelin sheaths (Below)
![](../pics/biopsy/inflammation/behcet/behcetwdacp.jpg)
Acid Phosphatase stain
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Nerve Ischemia, Local: Varied involvement of Cells in Different Fascicles
Also see:
Rheumatoid Vasculitis
![](../pics/biopsy/inflammation/behcet/behcetdifffasciche.jpg)
H&E stain
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Fascicular involvement: Varied
Left: Normal background staining of endoneurium
Right: Endoneurial Pallor with mild subperineurial edema
Wallerian Degeneration: Staining of myelin sheaths is lost
Vessels
Occluded artery &
Damaged veins
![](../pics/biopsy/inflammation/behcet/behcetdifffasatp.jpg)
ATPase pH 4.3 stain
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Fascicular involvement: Varied
Left: Normal to dark background staining of endoneurium
Right: Endoneurial Pallor
Epineurium
Neovascularization: Many small, ATPase+ vessels
![](../pics/biopsy/inflammation/behcet/behcetdifffasncam.jpg)
NCAM stain
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Differential Fascicular involvement: Varied loss of non-myelinating Schwann cells
Left: Diffuse distribution of non-myelinating Schwann cells in endoneurium
Right: Reduced numbers of non-myelinating Schwann cells in endoneurium
![](../pics/biopsy/inflammation/behcet/behcetdifffasvvg.jpg)
VvG stain
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Differential Fascicular involvement: Varied loss of Myelinated Axons
Left: Mild loss of myelinated axons
Right: Severe loss of myelinated axons
Above: Intrafascicular variation in loss of myelinated axons
![](../pics/biopsy/inflammation/behcet/behcetdifffasnfil.jpg)
Neurofilament stain
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Differential Fascicular involvement: Varied loss of Large & Small Axons (Above & Below)
Left, Above: Mild loss of myelinated axons; Normal numbers of small axons
Right, Above: Severe loss of all axons
Below: Fascicles with intrafascicular variation in loss of axons
![](../pics/biopsy/inflammation/behcet/behcetnfgncamrbsm.jpg)
Neurofilament (Green) + NCAM (Red) stain
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Damaged Fascicle
Endoneurium: Collapsed & Lost
Perineurium: Wavy & Irregular shape
Surrounding Epineurium: Neovascularization
Compare to:
Other fascicles in nerve
![](../pics/biopsy/inflammation/behcet/behcetfascdamvvghpsm.jpg)
VvG stain
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Schwann Cell Populations
![](../pics/biopsy/inflammation/behcet/behcetNCAM(g)P0(r)sm.jpg)
NCAM (Green), P0 (Red)
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Most Denervated Schwann Cells have not converted to a Denervated Phenotype
Little co-staining of P0 & NCAM in Schwann cells
![](../pics/biopsy/inflammation/behcet/behcetNF(g)MBP(r)sm.jpg)
Neurofilament (Green), Myelin Basic Protein (MBP) (Red)
Immature Schwann cells on many remaining axons
MBP stains on smaller axons with no myelin
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4/1/2024