Myopathy with NMO & Aquaporin-4 (AQP4) Antibodies
Muscle Fibers
![](../pics/biopsy/inflammation/aqp4/iimaqp4help.jpg)
H& E stain
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Pattern
Atrophy & Immaturity
More pathology at edges of fascicles
![](../pics/biopsy/inflammation/aqp4/iimaqp4pfahelp.jpg)
H & E stain
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![](../pics/biopsy/inflammation/aqp4/iimaqp4atp43lp.jpg)
ATPase pH 4.3 stain
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Perimysial Connective Tissue
![](../pics/biopsy/inflammation/aqp4/iimaqp4alplp.jpg)
Alkaline phosphatase stain
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Alkaline phospatase: Strong staining of perimysium & some neighboring endomysium
Acid phosphatase: Stains cells in perimysium & endomysium
![](../pics/biopsy/inflammation/aqp4/iimaqp4acplp.jpg)
Acid phosphatase stain
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![](../pics/biopsy/inflammation/aqp4/iimaqp4acpmp1.jpg)
Acid phosphatase stain
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Histiocytes
Acid phosphatase cells scattered in endomysium & perimysium
![](../pics/biopsy/inflammation/aqp4/iimaqp4acpmp2.jpg)
Acid phosphatase stain
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Muscle Fiber Pathology
![](../pics/biopsy/inflammation/aqp4/iimaqp4pfatrhemp.jpg)
H & E stain
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Small muscle fibers
Often immature (Basophilic)
Internal nuclei
Internal architecture
Sworled
Vacuoles & Aggregates
![](../pics/biopsy/inflammation/aqp4/iimaqp4fibvvglp.jpg)
VvG stain
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![](../pics/biopsy/inflammation/aqp4/iimaqp4nadhlp.jpg)
NADH stain
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![](../pics/biopsy/inflammation/aqp4/iimaqp4mfhemp.jpg)
H & E stain
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![](../pics/biopsy/inflammation/aqp4/iimaqp4fibshehp.jpg)
H & E stain
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![](../pics/biopsy/inflammation/aqp4/iimaqp4hemfhp.jpg)
H& E stain
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![](../pics/biopsy/inflammation/aqp4/iimaqp4nadhhp.jpg)
NADH stain
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![](../pics/biopsy/inflammation/aqp4/iimaqp4ampdahp.jpg)
AMPDA blue stain
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![](../pics/biopsy/inflammation/aqp4/iimaqp4mfvghp.jpg)
VvG stain
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![](../pics/biopsy/inflammation/aqp4/iimaqp4fibvvghp4.jpg)
VvG stain
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Cytoplasmic bodies
![](../pics/biopsy/inflammation/aqp4/iimaqp4cbgtmp.jpg)
Gomori trichrome blue stain
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Capillary pathology
Some capillaries are large & have thickened basal lamina (Arrow)
There is a
regional loss of endomysial capillaries in some areas
![](../pics/biopsy/inflammation/aqp4/iimaqp4capsabar.jpg)
Alcian blue stain
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![](../pics/biopsy/inflammation/aqp4/iimaqp4ulex1.jpg)
UEA1 stain
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Capillary pathology
Regional loss of endomysial capillaries, some perifascicular
UEA I also abnormally stains the surfaces of some muscle fibers
![](../pics/biopsy/inflammation/aqp4/iimaqp4ulex2.jpg)
UEA1 stain
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C5b-9 deposition
Connective tissue: Endomysium & Perimysium
Endomysial capillaries: Scattered
Muscle fibers: Patchy on surfaces
![](../pics/biopsy/inflammation/aqp4/iimaqp4c5b9.jpg)
C5b-9 stain
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MHC-I upregulation by muscle fibers
In regions with muscle fiber atrophy
![](../pics/biopsy/inflammation/aqp4/iimaqp4mhc1.jpg)
MHC1 stain
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Muscle autoantibodies
2/20/2021