MYH7 disorders
Gowers-Laing: Adult
Muscle fiber sizes
Varied: Small to Hypertrophied
Bimodal distribution
![](../pics/biopsy/myh7/myh7help.jpg)
H & E stain
|
![](../pics/biopsy/myh7/myh7he1a.jpg)
H & E stain
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Small muscle fibers
Often present in clusters
May be intermediate sized or very small
May be round,
polygonal or angular
![](../pics/biopsy/myh7/myh7he1.jpg)
H & E stain
|
![](../pics/biopsy/myh7/myh7he2.jpg)
H & E stain
|
Small muscle fibers
Varied shapes & sizes
![](../pics/biopsy/myh7/myh7gt.jpg)
Gomori trichrome stain
|
![](../pics/biopsy/myh7/myh7gt2.jpg)
Gomori trichrome stain
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Fiber sizes
Varied
Bimodal distribution
![](../pics/biopsy/myh7/myh7vvg.jpg)
VvG stain
|
![](../pics/biopsy/myh7/myh7nadh2.jpg)
NADH stain
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Small muscle fibers
Stain dark with NADH: Likely type I
![](../pics/biopsy/myh7/myh7nadh.jpg)
NADH stain
|
![](../pics/biopsy/myh7/myh7nadh3.jpg)
NADH stain
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Cores
In some muscle fibers within a group of type I fibers
Other fibers have irregular internal architecture
![](../pics/biopsy/myh7/myh7corenadh.jpg)
NADH stain
|
![](../pics/biopsy/myh7/myh7atp43lp3.jpg)
ATPase pH 4.3 stain
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Fiber types: Grouped
![](../pics/biopsy/myh7/myh7atp43lp.jpg)
ATPase pH 4.3 stain
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Small muscle fibers: Most are type I (Dark stained)
![](../pics/biopsy/myh7/myh7atp43.jpg)
ATPase pH 4.3 stain
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![](../pics/biopsy/myh7/myh7atp43b.jpg)
ATPase pH 9.4 stain
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Type I muscle fibers (Pale stained)
May be large or small
May be present in groups or clusters
![](../pics/biopsy/myh7/myh7atp94b.jpg)
ATPase pH 9.4 stain
|
Serial sections with different stains
![](../pics/biopsy/myh7/myh7atp94b2.jpg)
ATPase pH 4.3 stain
|
![](../pics/biopsy/myh7/myh7atp94c.jpg)
ATPase pH 9.4 stain
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Abnormal Fiber Types
1: Contain both MYH7 & MYH4
2A (No staining at ATPase pH 4.6): Not present
2: Express MYH2 & MYH4
H: Dark at both ATPase pH 9.4 & 4.6; Express MYH7, MYH2 & MYH1
H2: Express both MYH7 & MYH1
![](../pics/biopsy/myh7/myh7pas.jpg)
PAS stain
|
![](../pics/biopsy/myh7/myh7cox2.jpg)
Cytochrome oxidase stain
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MYH7 mutation: Childhood
![](../pics/biopsy/myh7/myh7childhe.jpg)
H&E stain
|
Fiber sizes
Varied
Bimodal distribution
![](../pics/biopsy/myh7/myh7childcr.jpg)
Congo red stain
|
Muscle fiber internal architecture
Irregular
"Smudged" regions with reduced staining
![](../pics/biopsy/myh7/myh7childgt.jpg)
Gomori trichrome stain
|
![](../pics/biopsy/myh7/myh7childnadh.jpg)
NADH stain
|
Muscle fiber internal architecture
May be coarse with variable dark & light-stained areas
Core-like pathology: Minicores; Eccentric cores
![](../pics/biopsy/myh7/myh7childnadhhp.jpg)
NADH stain
|
Muscle fiber internal architecture
Reduced mitochondrial staining in some areas
![](../pics/biopsy/myh7/myh7childcox.jpg)
Cytochrome oxidase stain
|
![](../pics/biopsy/myh7/myh7childatp94.jpg)
ATPase pH 9.4 stain
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Muscle fiber types
Type 2, especially 2B, fibers tens to be smaller than type 1
![](../pics/biopsy/myh7/myh7childatp43.jpg)
ATPase pH 4.3 stain
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![](../pics/biopsy/myh7/myh7childatp46.jpg)
ATPase pH 4.6 stain
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Neuromuscular junctions
Large & Dark stained for esterase
![](../pics/biopsy/myh7/myh7childest.jpg)
Esterase stain
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MYH7
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Neuromuscular home page
11/14/2021