Myotonia Congenita
CLCN-1: Gly230Glu Mutation, Dominant inheritance (Thomsen Syndrome)
52 year old patient
![](../pics/biopsy/myotcong/mcclcn06help.jpg)
H&E stain
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Muscle fiber morphology: Small, Irrregular-shaped, Clear regions in cytoplasm
Fiber Sizes: Mildly varied
![](../pics/biopsy/myotcong/mcclcn06he.jpg)
H&E stain
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![](../pics/biopsy/myotcong/mcclcn06gt.jpg)
Gomori trichrome stain
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Muscle fiber morphology Small, Irrregular-shaped or Rounded, Clear regions scatttered in fiber cytoplasm
![](../pics/biopsy/myotcong/mcclcn06gt2.jpg)
Gomori trichrome stain
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![](../pics/biopsy/myotcong/mcclcn06cr.jpg)
Congo red stain
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Muscle fiber morphology Small, Irrregular-shaped or Rounded, Clear regions scatttered in fiber cytoplasm
![](../pics/biopsy/myotcong/mcclcn06vvg.jpg)
VvG stain
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Muscle fiber morphology A few fibers have dark-stained punctate regions in cytoplasm
![](../pics/biopsy/myotcong/mcclcn06nadhlp.jpg)
NADH stain
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Muscle fibers: Internal architecture
Darker (Type 1) fibers: Punctate or Irregular linear staining
Lighter (Type 2) fibers: Linearization of internal architecture
![](../pics/biopsy/myotcong/mcclcn06nadh2.jpg)
NADH stain
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![](../pics/biopsy/myotcong/mcclcn06nadh3.jpg)
NADH stain
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![](../pics/biopsy/myotcong/mcclcn06atp94.jpg)
ATPase pH 9.4 stain
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Muscle fibers
Irrregular "cracks": More prominent in type I fibers
![](../pics/biopsy/myotcong/mcclcn06atp43.jpg)
ATPase pH 4.3 stain
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Muscle fibers
No 2C fibers
![](../pics/biopsy/myotcong/mcclcn06atp46lp.jpg)
ATPase pH 4.6 stain
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Muscle fibers
Many 2B fibers fibers
![](../pics/biopsy/myotcong/mcclcn06nmjest.jpg)
Esterase stain
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Neuromuscular junctions
Several patches of esterase staining
![](../pics/biopsy/myotcong/mcclcn06acp.jpg)
Acid phospbhatasestain
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Muscle fibers
No lipofuscin
![](../pics/biopsy/myotcong/mcclcn06spindlevvg.jpg)
VvG stain
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Muscle spindle
Unusual feature: Small, thick-walled vessels inside spindle
Myotonia Congenita
CLCN-1: Gly230Glu Mutation, Dominant inheritance (Thomsen Syndrome)
15 year old patient
![](../pics/biopsy/myotcong/mcclcn94he.jpg)
H&E stain
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Muscle fibers
Varied size
Few small angular fibers
![](../pics/biopsy/myotcong/mcclcn94gt.jpg)
Gomori trichrome stain
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Muscle fibers
Internal architecture: Prominently stained
![](../pics/biopsy/myotcong/mcclcn94vvg.jpg)
VvG stain
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![](../pics/biopsy/myotcong/mcclcn94nadhlp.jpg)
NADH stain
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Muscle fibers: Internal architecture
Type 1 fibers: Dark & Continuous (Immature)
Type 2 fibers: Punctate or Irregular
![](../pics/biopsy/myotcong/mcclcn94nadh2.jpg)
NADH stain
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![](../pics/biopsy/myotcong/mcclcn94nadh.jpg)
NADH stain
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![](../pics/biopsy/myotcong/mcclcn94atp94b.jpg)
ATPase pH 9.4 stain
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Muscle fibers
Type 2 fibers: Predominance; Mildly larger than type 1
![](../pics/biopsy/myotcong/mcclcn94atp43.jpg)
ATPase pH 4.3 stain
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![](../pics/biopsy/myotcong/mcclcn94atp46.jpg)
ATPase pH 4.6 stain
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Muscle fibers
Many Type 2B fibers: Larger than other fiber types
![](../pics/biopsy/myotcong/mcclcn94acp.jpg)
Acid phosphatase stain
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Muscle fibers
No lipofuscin
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5/10/2020