Chronic Immune Demyelinating Polyneuropathy (CIDP), Adult
CIDP: Nerve morphology
 H&E stain |
Some regions are pale
Myelinated axons: Patchy loss
Perineurium: Thin & pale stained in regions
 Gomori trichrome stain |
Small & Varied sizes
Scattered in endoneurium
 Gomori trichrome stain |
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 large thickly-myelinated axons
Thick Myelin sheaths containing MBP are mostly lost
MBP is expressed in
Many immature non-myelinating Schwann cells: Often surrounding single small axons
Thin myelin sheaths on regenerated or remyelinated axons
 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 |
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 |
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 on Green background) co-stain for NCAM & P0
Remaining myelin (Red): Shows co-staining with NCAM (Yellow) suggesting remyelination
Normally unmyelinated axons (Green): Occur in small clusters
 NCAM (Green) + P0 (Red) stain |
Subperineurial edema
 H&E stain |
Subperineurial edema |
 Toluidine blue stain |
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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7/28/2026