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CIDP: Subacute Onset

Note: Patient features

• Clinical
  • 55 yo female
  • Onset: Progressive over 8 weeks
  • Weakness: Severe; Proximal & Distal
  • Corticosteroid treatment: Improvement to normal strength & ADL
• NCV
  • Demyelination
    • Conduction velocities, motor: Variably slowed (12 to 31 M/s)
    • Distal latencies: Long
    • Temporal dispersion
  • Axon loss
    • SNAPs: Reduced amplitude or Absent
• Pathology
  • Demyelination
    • Diffuse
    • Axons: Unmyelinated & Hypomyelinated
  • Axon loss: Variable
  • Subperineurial edema
  • Vessels
    • Endoneurial: Diameter enlarged; Endothelial cells large
    • Epineurial: Normal structure; No immune cells
  • Muscle

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Nerve: Axon loss, Variable & Myelin loss, Diffuse Neurofilament stain Axons (Same nerve as on right )   Variable loss of large & small axons within & among fascicles   Large axons:     Demyelinated     Preservation of some large axons without surrounding clear myelin rim

Toluidine blue stain Myelinated axons   Apparent nearly complete myelinated axon loss in some fascicles Subperineurial edema

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Differential fascicular involvement: Variable loss of myelinated axons among fascicles

VvG stain

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Nerve: Variable loss of large axons

Neurofilament stain	Neurofilament stain
Axon Loss Some fascicles have more loss of large (thick) axons (Right) than others (Left) Small axons are moderately reduced in both fascicles

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Large axons: Demyelinated & Poorly formed onion bulbs

Toluidine blue stain	Toluidine blue stain
Demyelinated axons Demyelinated, or thinly myelinated axons, often surrounded by poorly formed oniuon bulbs and Schwann cell nuclei

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Subperineurial Edema

H & E stain Subperineurial Edema: Clear region beneath long area of perineurium

Toluidine blue stain Subperineurial Edema & Few normally myelinated axons

H & E stain Region of subperineurial edema:   Contains amorphous material and small vessels

Toluidine blue stain Intrafascicular septa:   Widened & Cellular   Contains enlarged endoneurial vessel Myelinated Axons: Few remaining; Small

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Endoneurial vessels: Large size; Abnormal endothelial cells with large nuclei

H&E stain

Endoneurial capillaries: Enlarged with large endothelial cells VvG stain

Gomori trichrome stain

Gomori trichrome stain

H&E stain

Endoneurial capillaries: Alkaline phosphatase stained Alkaline phosphatase stain

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Endoneurial cells: Scattered small & punctate acid phosphatase staining

Acid phosphatase stain

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VvG stain Artery	VvG stain Vein
Epineurial vessels: Normal	VvG stain Smaller epineurial vessels

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CIDP Sub-Acute Onset: Muscle

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Atrophy: Most muscle fibers
Nuclei: Large
Sarcolemma: Irregular

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Internal architecture: Irregular
Fiber sizes: Type 2 often smaller than type 1

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Neuromuscular junctions: Patchy; mildly elongated

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9/22/2015