Neuromuscular

Chronic Immune Demyelinating Polyneuropathy (CIDP), Adult

Morphology & Axons
Myelin & Onion bulbs
Subperineurial edema
 Other CIDP pathology
Childhood
Demyelination, Active
Differential fascicular Δ
Onion bulbs
Segmental demyelination
Sub-acute onset
Thin myelin sheaths
Tomacula
CIDP: Nerve morphology

H&E stain
  Endoneurium
    Some regions are pale
    Myelinated axons: Patchy loss
  Perineurium: Thin & pale stained in regions

Gomori trichrome stain
Onion bulbs, Small (Arrows)
  Small & Varied sizes
  Scattered in endoneurium

Gomori trichrome stain
Myelinated axons: Patchy, severe loss
Onion bulbs, Small
  Scattered in endoneurium

VvG stain
CIDP
  Myelinated axon loss     There are no large myelinated axons
    Remaining small axons are hypomyelinated
  Subperineurial edema: Narrow; Surrounds much of fascicle

Toluidine blue stain
CIDP: Loss of the largest myelinated axons
  Myelin containing MBP is mostly lost
  With loss of large axons many non-myelinating Schwann cells express small amounts of MBP_

Neurofilaments (Green) + MBP (Red) stain
Myelin Pathology
  Onion bulbs
  Myelin sheath: Thin

Thinly myelinated axons.
Axon loss.
Thinly myelinated axons.
Axon loss: Patchy
Onion bulbs: Small

Neurofilaments (Green) + NCAM (Red) stain
Onion bulbs: Many small
  Most axons, even intermediate sized ones, are surounded by NCAM-stained Schwann cells
    NCAM normally surround only the smallest axons
Axon loss: The largest axons are completel lost

Neurofilaments (Green) + NCAM (Red) stain
Onion bulbs: Many small
  Many axons are surrounded by P0 even though myelinated axons are mostly lost
  Schwann cells in onion bulbs: Similar to Büngner band Schwann cells (Yellow) with co-staining for NCAM & P0

NCAM (Green) + P0 (Red) stain

Toluidine blue stain
Onion bulbs
  Surround some axons
  Varied sizes
  Some contain no axon
  Most axons in onion bulbs are hypomyelinated (Thin myelin sheath)

Toluidine blue stain
CIDP: Axon loss, Chronic: Schwann cells
  Büngner band & Onion bulb Schwann cells (Yellow) co-stain for NCAM & P0
Normally unmyelinated axons (Green): Occur in small clusters

NCAM (Green) + P0 (Red) stain
Subperineurial edema

H&E stain
Subperineurial edema

Toluidine blue stain
Subperineurial edema: Mild
Onion bulbs
Endoneurial Microvessels: Mildly large

Toluidine blue stain
CIDP, Chronic: No inflammation

Acid phosphatase stain
CIDP: Muscle

ATPase pH 9.4 stain
Type 1 muscle fiber predominance

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4/16/2021