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Chronic Immune Polyneuropathy with Vesicular Demyelination ¹, Schwann-process Bulbs & Axon Vesicles

Myelin sheaths   Patterns   Thin   Vesicular pathology   Demyelination   Molecular Schwann cells   Process bulbs     Molecular   Nuclei increased Axons   Vescicle-like structures in axoplasm Histology Other

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Myelin Sheaths: Thin

Toluidine blue stain

Myelination
  Many thinly myelinated large axons

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Toluidine blue stain

Myelination
  Many thinly myelinated axons
  Scattered demyelinated axons (Arrow above)
  Many large axons have blue-stained surrounding tissue, often containing Schwann cell nuclei
Myelin Structure
  Irregular around some axons (Arrows below)

Toluidine blue stain

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Myelin Sheaths: Thin
Schwann cells: Processes & nuclei surround thinly myelinated axons

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Schwann-process Bulbs
  Schwann cell processes & collagen surround thinly myelinated axons
Schwann-process Bulbs
  Schwann cell processes & collagen surround thinly myelinated axons

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Myelin Basic Protein on & around Axons
  Present on larger axons without myelin sheath (Yellow) (Arrow)
  Thin layer (Red) surrounds other large axons (Immature Schwann cell processes)

Neurofilament Green; MBP Red

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NCAM on & around Axons
  Present (Red) around a few larger axons (Arrow)
  Small axons
    Loss: NCAM regions (Red) are empty or have only a few axons
    Some remaining small axons are beaded (Yellow)

Neurofilament Green; NCAM Red

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P0 Protein around Axons
  Mild-Moderate loss of larger axons

Neurofilament Green; P0 Red

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Schwann cell processes
  Scattered in collagen around axon

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Myelin Pathology: Vesicular Vesicular pathology
  In inner region of myelin sheath

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Myelin: Vesicular pathology
  Replaces inner region of myelin sheath
Schwann cell processes
  Surround myelinated axon
Axoplasm
  Contains vesicular structures

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Myelin
  Vesicular changes: Replace regions of thin myelin sheath
Axoplasm: Contains vesicles
Myelin
  Vesicular changes: Within & at external regions of myelin sheath

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Axon
  Large
  Axoplasm: Abnormal with vesicles
Myelin
  Vesiculated near axon

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Myelin Sheath: Absent
Schwann cell processes: Surround demyelinated axon
Schwann cell nuclei: Multiple; In and around Schwann cell processes

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Myelin, Molecular
  Abnormal co-expression of P0 & NCAM (Yellow) in sheaths (Red)

NCAM Green; P0 Red

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Axoplasm Pathology

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Myelin Sheath
  Thin
  Variable width
Schwann cells
  Processes: Surround axon
  Nuclei: Multiple present
Axon
  Large
  Axoplasm: Abnormal with vesicles

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Myelin Sheath
  Thin
Schwann cells
  Processes: Surround axon
Axon
  Large
  Axoplasm: Abnormal with vesicles

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Myelin Sheath
  Thin
Schwann cells
  Few Processes: Around axon
Axon
  Large
  Axoplasm: Abnormal with many vesicles

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Myelin sheath
  Shape: Flat
  Little axoplasm visible inside

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H&E stain

Endoneurial edema

H&E stain

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Gomori trichrome stain

Myelinated Axon loss
  Moderate
Myelin Sheaths
  Many abnormal: Reduced (Red) staining

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VvG stain

Myelinated Axon loss
  Moderate

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VvG stain

Endoneurial Microvessel
  Occluded

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Acid phosphatase stain

Myelin: Mild, diffuse acid phosphatase stain

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ATPase pH 4.3 stain

Endoneurium: Normal

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Neurofilament stain

Large axons
  Reduced number
  Remaining large axons have no, or little associated myelin (Arrow)

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NCAM stain

NCAM abnormally stains remaining myelin sheaths (Arrow)

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References
1. Ann Neurol 1996;39:625-35

4/20/2025