CIDP: Nerve morphology
![](../pics/biopsy/myelin/cidpsterresp/cidpsterresphe.jpg)
H&E stain
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Endoneurium
Some regions are pale
Myelinated axons: Patchy loss
Perineurium: Thin & pale stained in regions
![](../pics/biopsy/myelin/cidpsterresp/cidpsterrespgtar.jpg)
Gomori trichrome stain
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Onion bulbs, Small (Arrows)
Small & Varied sizes
Scattered in endoneurium
![](../pics/biopsy/myelin/cidpsterresp/cidpsterrespgt2ar.jpg)
Gomori trichrome stain
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Myelinated axons: Patchy, severe loss
Onion bulbs, Small
Scattered in endoneurium
![](../pics/biopsy/myelin/cidpsterresp/cidpsterrespvvg2.jpg)
VvG stain
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CIDP
Myelinated axon loss
There are no large myelinated axons
Remaining small axons are hypomyelinated
Subperineurial edema: Narrow; Surrounds much of fascicle
![](../pics/biopsy/myelin/cidpsterresp/cidpsterresptbvlp.jpg)
Toluidine blue stain
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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_
![](../pics/biopsy/myelin/cidpsterresp/cidpsterrespnfilgrmbpred.jpg)
Neurofilaments (Green) + MBP (Red) stain
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Myelin Pathology
Onion bulbs
Myelin sheath: Thin
![](../pics/biopsy/nerve/cidp/demoniontbsm.jpg)
Thinly myelinated axons.
Axon loss.
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![](../pics/biopsy/nerve/cidp/focdemtbsm.jpg)
Thinly myelinated axons.
Axon loss: Patchy
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Onion bulbs: Small
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![](../pics/biopsy/myelin/cidpsterresp/cidpsterrespnfilgncamred1.jpg)
Neurofilaments (Green) + NCAM (Red) stain
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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
![](../pics/biopsy/myelin/cidpsterresp/cidpsterrespnfilgncamred2.jpg)
Neurofilaments (Green) + NCAM (Red) stain
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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
![](../pics/biopsy/myelin/cidpsterresp/cidpsterrespnfilgrp0red1.jpg)
NCAM (Green) + P0 (Red) stain
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![](../pics/biopsy/myelin/cidpsterresp/cidpsterresptb.jpg)
Toluidine blue stain
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Onion bulbs
Surround some axons
Varied sizes
Some contain no axon
Most axons in onion bulbs are hypomyelinated (Thin myelin sheath)
![](../pics/biopsy/myelin/cidpsterresp/cidpsterresptbhp.jpg)
Toluidine blue stain
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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
![](../pics/biopsy/myelin/cidpsterresp/cidpsterrespncamgp0red.jpg)
NCAM (Green) + P0 (Red) stain
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Subperineurial edema
![](../pics/biopsy/nerve/cidp/cidphehp.jpg)
H&E stain
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Subperineurial edema
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![](../pics/biopsy/myelin/cidpsterresp/cidpsterresptbhp5.jpg)
Toluidine blue stain
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Subperineurial edema: Mild
Onion bulbs
Endoneurial Microvessels: Mildly large
![](../pics/biopsy/myelin/cidpsterresp/cidpsterresptbhp6.jpg)
Toluidine blue stain
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CIDP, Chronic: No inflammation
![](../pics/biopsy/myelin/cidpsterresp/cidpsterrespacp.jpg)
Acid phosphatase stain
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CIDP: Muscle
![](../pics/biopsy/nerve/cidp/cidp1predomatp94.jpg)
ATPase pH 9.4 stain
Type 1 muscle fiber predominance
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4/16/2021