U1RNP antibodies: Muscle Pathology
Endomysial Capillary Pathology with Minimal Myopathy
Endomysial Capillaries
Morphology: Large; Moderately thick walls
Endothelium
Acid phosphatase
ATPase
Ulex stain: Capillaries Large & Reduced numbers
MxA stain: Increased
C5b-9 deposition
Muscle Fibers
Morphology: Normal
MHC Class I: Increased expression
![](../pics/biopsy/inflammation/u1rnp/u1rnpasyxhe.jpg)
H&E stain
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Endomysial Capillaries
Large
Basal lamina & Endothelial cells: Prominent
Scattered through muscle
Muscle fibers
Size variation: Moderate
Smaller fibers: Intermediate size
![](../pics/biopsy/inflammation/u1rnp/u1rnpasyxhehp.jpg)
H&E stain
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![](../pics/biopsy/inflammation/u1rnp/u1rnpgtmp.jpg)
Gomori trichrome stain
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Endomysial Capillaries
Large
Basal lamina & Endothelial cells: Prominent
Scattered through muscle
Muscle fibers
Size variation: Moderate
Smaller fibers: Intermediate size
![](../pics/biopsy/inflammation/u1rnp/u1rnpvvg.jpg)
VvG stain
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![](../pics/biopsy/inflammation/u1rnp/u1rnpacpmp1.jpg)
Acid Phosphatase stain
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Endomysial Capillaries
Endothelial cells: Acid phosphatase staining
![](../pics/biopsy/inflammation/u1rnp/u1rnpacphp.jpg)
Acid Phosphatase stain
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![](../pics/biopsy/inflammation/u1rnp/u1rnpasyxulexlp.jpg)
Ulex stain
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Endomysial Capillaries (Ulex stain): U1RNP patient above; Control below
Numbers: Reduced
Stain intensity: Abnormally pale
Size: Large
![](../pics/biopsy/inflammation/u1rnp/u1rnpasyxulexcontlp.jpg)
Ulex stain
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![](../pics/biopsy/inflammation/u1rnp/u1rnpasyxulexmp.jpg)
Ulex stain
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Endomysial Capillaries (Ulex stain): U1RNP patient
Numbers: Reduced
Stain intensity: Abnormally pale
Size: Large
![](../pics/biopsy/inflammation/u1rnp/u1rnpasyxulexmp2.jpg)
Ulex stain
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Endomysial Capillaries (Ulex stain): U1RNP patient above; Control below
Numbers: Reduced
Stain intensity: Abnormally pale
Size: Large
Control muscle (Below): Dark staining of small capillaries
![](../pics/biopsy/inflammation/u1rnp/u1rnpasyxulexcontmp.jpg)
Ulex stain
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![](../pics/biopsy/inflammation/u1rnp/u1rnpasyxmxalp.jpg)
MxA stain
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MxA stain: U1RNP patient
Capillary-associated cells: Dark stain
Muscle fibers: Mild cytoplasm stain
![](../pics/biopsy/inflammation/u1rnp/u1rnpasyxmxa.jpg)
MxA stain
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MxA stain (Ulex stain): U1RNP patient above; Control below
Capillary-associated cells: Dark stain
Muscle fibers: Mild cytoplasm stain
Control muscle (Below): No staining of capillaries or muscle fibers
![](../pics/biopsy/inflammation/u1rnp/mxanl.jpg)
MxA stain
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![](../pics/biopsy/inflammation/u1rnp/u1rnpasyxc5b9lp.jpg)
C5b-9 stain
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C5b-9 stain: U1RNP patient
Endomysial Capillary-associated
Muscle fibers: No staining
![](../pics/biopsy/inflammation/u1rnp/u1rnpasyxc5b9hp.jpg)
C5b-9 stain
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![](../pics/biopsy/inflammation/u1rnp/u1rnpatp43.jpg)
ATPase pH 4.3 stain
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Endomysial Capillaries: Mild ATPase staining
Perimysial Connective Tissue: Replaced by fat (Above)
![](../pics/biopsy/inflammation/u1rnp/u1rnpasyxatp43.jpg)
ATPase pH 4.3 stain
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![](../pics/biopsy/inflammation/u1rnp/u1rnpnadhhp.jpg)
NADH stain
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Endomysial Capillaries: Mild NADH staining
Muscle fibers: Mildly coarse internal architecture
![](../pics/biopsy/inflammation/u1rnp/u1rnpnadhmp.jpg)
NADH stain
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![](../pics/biopsy/inflammation/u1rnp/u1rnpasyxest.jpg)
Esterase stain
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Neuromuscular Junctions: Normal
Muscle fibers: MHC1 upregulation
![](../pics/biopsy/inflammation/u1rnp/u1rnpasyxmhc1.jpg)
MHC I stain
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Myopathy with Capillary Pathology
![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpmyophelp.jpg)
H&E stain
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Active Myopathy: Features
Capillaries
Muscle fibers
Connective tissue
Inflammation
![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpgtmp.jpg)
Gomori trichrome stain
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![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpvvglp.jpg)
VvG stain
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Capillary Pathology
![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpmyopcaphehp.jpg)
H&E stain
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Endomysial Capillaries: Large size
![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpvvgcapshp.jpg)
VvG stain
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![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpvvghp2.jpg)
VvG stain
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Endomysial Capillaries: Acid phosphatase stains endothelium
![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpacphpcaps.jpg)
Acid phosphatase stain
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Endomysial Capillaries: ATPase stains endothelium
![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpatp43hp.jpg)
ATPase pH 4.3 stain
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Endomysial Capillaries: Ulex lectin shows large size & Reduced numbers
![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpulexlp.jpg)
UEA-I stain
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![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpulexhp1.jpg)
UEA-I stain
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Muscle Fiber Pathology
![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpvvgmp.jpg)
VvG stain
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Muscle Fiber Pathology
Sizes: Varied
Many immature fibers
Necrosis: Scattered fibers
Myonuclei: Large
![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpmyopnechemp.jpg)
H&E stain
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Muscle Fiber Pathology
Necrotic fibers invaded & replaced by histiocytes
![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpacpmp.jpg)
Acid phosphatase stain
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Muscle Fiber Pathology
MHC Class I: Upregulated by muscle fibers
![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpmhc1.jpg)
MHC Class I stain
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Muscle Pathology
C
5b-9 stains
Cytoplasm of necrotic muscle fibers
Endomysial connective tissue
![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpc5b9.jpg)
C5b-9 stain
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Perimysial Connective Tissue Pathology
![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpperimyshe.jpg)
H&E stain
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Perimysial Pathology
Perimysial Connective Tissue
Structure: Damaged
Contains: Large, Scattered Histiocytes
Stains for: Alkaline phosphatase (Below)
![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpalp.jpg)
Alkaline phosphatase stain
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![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpmyoppvhemp.jpg)
H&E stain
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Inflammation
Lymphocytes: Surround perimysial vessel
![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpgthp.jpg)
Gomori trichrome stain
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![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpvvghp.jpg)
VvG stain
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Inflammation
Lymphocytes: CD4 stains many endomysial cells
![](../pics/biopsy/inflammation/u1rnp/u1rnpmyop/u1rnpcd4.jpg)
CD4 stain
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12/17/2023