Neuromuscular

Acute Immune Neuropathies

AIDP
AMN
AMSAN
Demyelination
  Active

Acute Immune Demyelinating Polyneuropathy (AIDP)


H&E stain
Endoneurium: Granular myelin remnants
Perineurium, Epineurium & Vessels: Normal

H&E stain


Gomori trichrome stain
Myelin remnants: More staining with VvG than Gomori trichrome

VvG stain

Large & Small Axons
  Relatively preserved compared to myelin loss
  Focal loss in some endoneurial areas

Neurofilament stain


Acid phosphatase stain
Histiocytic cells: Associated with myelin remnants

Acid phosphatase stain

CD163 stain

Macrophage: Adherent to myelin sheath

Active Demyelination: Macrophage-mediated Myelin Stripping
Macrophage process: Extends under outer myelin layer (Arrows)


Toluidine blue stain
Subperineurial edema: Separation between endoneurium & perineurium
Endoneurial vessels & Endothelial cells: Large

Toluidine blue stain


Toluidine blue stain
Differential fascicular involvement: More loss of myelin in some fascicles than others

Toluidine blue stain

Demyelinated axons
  May be near cells containing myelin debris
Demyelinated axons

Myelin debris: Multiple partially degraded myelin fragments in phagocytic cells


Toluidine blue stain
Lipid debris: Multiple rounded regions in phagocytic cells

Acute Motor > Sensory Axonal Neuropathy with serum IgG binding to GalNAc-GD1a ganglioside

Sensory nerve: Axons relatively preserved


Toluidine blue stain
Subperineurial edema

Toluidine blue stain


Gomori trichrome stain
Differential fascicular involvement: More loss of myelinated axons in some fascicles than others

VvG stain

Few phagocytic cells

Acid phosphatase stain

Large & Small axons: Preserved numbers

Neurofilament stain

C5b-9 stain: Reduced on perineurium
Patient
Control


VvG stain
Polyglucosan bodies: Located in axons in intramuscular nerve

PAS stain

Acute Motor-Sensory Axonal Neuropathy (AMSAN)

From: Chunyu Cai, Dallas

Gomori trichrome stain
Differential fascicular involvement: More loss of myelinated axons in some fascicles than others


H& E stain
Subperineurial edema


H& E stain
Wallerian Degeneration: Myelin ovoids

Trichrome stain

Wallerian Degeneration: Phagocytic cells associated with myelin debris

Myelin ovoids

Loss of myelinated axons

Myelinated axons: Reduced numbers

Macrophages
  Marginated in vessel
  Extravasated in endoneurium

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2/3/2016