FACIOSCAPULOHUMERAL (FSH) DYSTROPHY
FSH: Adult, Moderate severity
![](../pics/biopsy/fsh/fshadulthelp.jpg)
H&E stain
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Muscle fibers
Size: Varied; Atrophy & Hypertrophy
Pathology: Necrosis, Regeneration & Persistent immaturity
![](../pics/biopsy/fsh/fshadultvvglp.jpg)
VvG stain
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![](../pics/biopsy/fsh/fshvarfibsizeinflamlp.jpg)
H&E stain
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![](../pics/biopsy/fsh/fshvarfibsizeinflam.jpg)
H&E stain
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![](../pics/biopsy/fsh/fshhereg3.jpg)
H&E stain
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Muscle fibers
Size: Varied; Atrophy & Hypertrophy
Regeneration: Basophilic muscle fibers
Endomysial connective tissue: Moderately increased
Inflammation: Around smaller, intermediate-sized vessels, not arteries or veins
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![](../pics/biopsy/fsh/fshpvinfvvg.jpg)
VvG stain
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Inflammation: Perivascular
Location
Around small perimysial vessels with no elastin in their wall (Above)
Not usually around arteries or veins (Below)
Cell types
Mononuclear: Especially CD4 & CD8
Large with large nuclei: ? Muscle regeneration
![](../pics/biopsy/fsh/fshinfcr.jpg)
Congo red stain
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Capillaries
![](../pics/biopsy/fsh/fshcappathvvg.jpg)
VvG stain
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Capillary pathology
Multiple large endomysial capillaries
![](../pics/biopsy/fsh/fshadcapinfvvg.jpg)
VvG stain
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Capillary pathology
![](../pics/biopsy/fsh/fshdcaps43lp.jpg)
ATPase pH 4.3 stain
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Endomysial Capillaries
Dark, abnormal staining for ATPase
![](../pics/biopsy/fsh/fshd43mp.jpg)
ATPase pH 4.3 stain
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![](../pics/biopsy/fsh/fshd43hp.jpg)
ATPase pH 4.3 stain
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Necrotic muscle fibers
Scattered
Histiocytic cells slow to migrate away from necrotic fiber
More common in muscles with less fibrosis
![](../pics/biopsy/fsh/fshhenec2.jpg)
H&E stain
Necrosis: Early
Pale muscle fiber cytoplasm
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![](../pics/biopsy/fsh/fshhenec1.jpg)
H&E stain
Necrosis
Muscle fibers replaced by histiocytic cells
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![](../pics/biopsy/fsh/fshacpnec.jpg)
Acid phosphatase stain
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![](../pics/biopsy/fsh/fshnecrosiscr.jpg)
Congo red stain
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Necrotic muscle fiber
Replaced by esterase-positive histiocytic cells
![](../pics/biopsy/fsh/fshnecesthp.jpg)
Esterase stain
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![](../pics/biopsy/fsh/FSHATP43.jpg)
ATPase, pH 4.3 stain
Small & large fibers are both types.
A few immature, type 2C, fibers are present. (Intermediate staining; Arrow)
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![](../pics/biopsy/fsh/FSHATP94a.jpg)
ATPase pH 9.4 stain, Patient 1
Large fibers: Types I & II.
Small fibers: Types I & II.
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![](../pics/biopsy/fsh/fshatp94b.jpg)
ATPase, pH 9.4 stain
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FSH: Fiber pathology
![](../pics/biopsy/fsh/fshfib.jpg)
H&E stain
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FSH fibers: Basophilic muscle fibers with large, often clustered, nuclei
![](../pics/biopsy/fsh/fshadfibgt.jpg)
Gomori trichrome stain
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![](../pics/biopsy/fsh/fshadultfib2.jpg)
H&E stain
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![](../pics/biopsy/fsh/fshnadhmp.jpg)
NADH stain
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Muscle fiber internal architecture
Larger fibers
Pale centers (Above
Whorled or Irregular (Below)
Small fibers: Dark stained
Necrotic muscle fiber: Pale stained (Top left)
![](../pics/biopsy/fsh/fshnadh3.jpg)
NADH stain
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MHC-1: Upregulation by muscle fibers
On the rim of all muscle fibers
In the cytoplasm of smaller, immature fibers.
![](../pics/biopsy/fsh/fshadultmhc1.jpg)
MHC-1 stain
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![](../pics/biopsy/fsh/FSHperimysiallipidh.jpg)
Sudan black stain
Fat replaces perimysial connective tissue
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FSH: Later stage
![](../pics/biopsy/fsh/fshlatehelp2.jpg)
H&E stain
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Varied pathology among fascicles
![](../pics/biopsy/fsh/fshlatenadh2.jpg)
NADH stain
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Muscle fiber sizes: Marked variation
Endomysial connective tissue: Increased between muscle fibers
Inflammation: Foci surrounding smaller perimysial vessels
![](../pics/biopsy/fsh/fshlatehelp.jpg)
H&E stain
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![](../pics/biopsy/fsh/fshvarfibsizehe.jpg)
H&E stain
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Fiber sizes: Marked variation
![](../pics/biopsy/fsh/FSHvarfshe.jpg)
H&E stain
Varied fiber size: Marked Hypertrophic & Very small fibers
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![](../pics/biopsy/fsh/FSHnadh2.jpg)
NADH stain
Hypertrophic fibers: Often have pale centers.
Small fibers: Dark & Pale stained
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![](../pics/biopsy/fsh/FSH94b.jpg)
ATPase pH 9.4 stain, Patient 2
Large fibers: Types I & II.
Small fibers: Often type II.
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![](../pics/biopsy/fsh/fshgthp.jpg)
Gomori trichrome stain
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Muscle fiber sizes: Varied
Small muscle fibers: Round; Dark stained on NADH
Hypertrophied muscle fibers: Very large; clear centers on NADH
![](../pics/biopsy/fsh/fshnadhhp.jpg)
NADH stain
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Varied muscle fiber sizes
Small rounded muscle fibers
Vary large, hypertrophied muscle fibers
![](../pics/biopsy/fsh/fshlatevvgmp2.jpg)
VvG stain
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Inflammation: Foci surrounding smaller perimysial vessels
![](../pics/biopsy/fsh/fshlatehehp.jpg)
H&E stain
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Inflammation: Foci surrounding smaller perimysial vessels
Endomysial connective tissue: Increased betwen muscle fibers
![](../pics/biopsy/fsh/fshlategtmp.jpg)
Gomori trichrome stain
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Inflammation: Perimysial focus
![](../pics/biopsy/fsh/fshlateinfcr.jpg)
Congo red stain
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Inflammatory foci: Mostly lymphocytes; Minority of cells stain for acid phosphatase & esterase
![](../pics/biopsy/fsh/fshlateinfest.jpg)
Esterase stain
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![](../pics/biopsy/fsh/fshlateinfvvgmp.jpg)
VvG stain
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Inflammation: Foci surrounding smaller perimysial vessels
Larger vessels: Normal
![](../pics/biopsy/fsh/fshlatenlvseevvg.jpg)
VvG stain
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Intermediate-Sized vessels & Intramuscular Nerves: Normal in FSH
![](../pics/biopsy/fsh/fshvessvvg.jpg)
VvG stain
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![](../pics/biopsy/fsh/fshlateneche.jpg)
H&E stain
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FSH: Necrosis of some hypertrophied muscle fibers
![](../pics/biopsy/fsh/fshlateneche2.jpg)
H&E stain
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![](../pics/biopsy/fsh/fshlatevvgmp.jpg)
VvG stain
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Active myopathy
Necrotic muscle fibers
Immature, regenerating muscle fibers: Darker stained, rounded, small muscle fibers
Acid phosphatase positive cells scattered in endomysium
![](../pics/biopsy/fsh/fshlateinfacp.jpg)
Acid phosphatase stain
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![](../pics/biopsy/fsh/fshlatenecest.jpg)
Esterase stain
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Necrotic muscle fibers: Replaced by histiocytic cells that stain for Acid phosphatase & Esterase
![](../pics/biopsy/fsh/fshlateacpmp.jpg)
Acid phosphatase stain
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![](../pics/biopsy/fsh/fshlatenadhmp.jpg)
NADH stain
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Internal architecture
Small muscle fibers: Varied staining, from normal to dark
Hypertrophied muscle fibers: Often have
clear central regions
![](../pics/biopsy/fsh/fshalphp.jpg)
Alkaline phosphatase stain
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Immature muscle fibers
Small, rounded
Cytoplasm: Stains for alkaline phosphatase
![](../pics/biopsy/fsh/fshlatealp.jpg)
Alkaline phosphatase stain
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Immature muscle fibers
Small, rounded
Cytoplasm: Darker staining on VvG
![](../pics/biopsy/fsh/fshimmatvvghp.jpg)
VvG stain
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![](../pics/biopsy/fsh/fshlateatp94.jpg)
ATPase pH 9.4 stain
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Fiber types
Large fibers: Types I & II
Small fibers: More commonly type II
![](../pics/biopsy/fsh/fshlateatp43.jpg)
ATPase pH 4.3 stain
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Congenital FSH
FSHD, Congenital: Myopathy
2 year old female
![](../pics/biopsy/fsh/fshconghe.jpg)
H&E stain
Muscle fiber size: Varied
Many small basophilic fibers
Mononuclear inflammatory cells
Around smaller, intermediate sized perimysial vessel (Above)
In endomysium (Below)
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![Congenital FSH](../pics/biopsy/fsh/fshcongv.jpg)
H&E stain
Varied muscle fiber size.
Basophilic (immature) fibers.
No hypertrophy.
Endomysial inflammation.
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![Congenital FSH: ATPase](../pics/biopsy/fsh/fshconatpv.jpg)
ATPase pH 9.4 stain
Smaller fibers are Type I & II
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![](../pics/biopsy/fsh/fshconggtlp.jpg)
Gomori trichrome stain
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Myopathology patterns
![](../pics/biopsy/fsh/fshcongmfhemp.jpg)
H&E stain
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Fiber size
Varied
Small fibers: Rounded; Some basophilic
Nuclei: Irregular shapes; Large; One or several internal
![](../pics/biopsy/fsh/fshcongmfhemp2.jpg)
H&E stain
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Endomysial cell clusters
![](../pics/biopsy/fsh/fshcongmfhemp3.jpg)
H&E stain
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Small muscle fibers: Basophilic cytoplasm; Large nuclei
![](../pics/biopsy/fsh/fshcongbfhemp.jpg)
H&E stain
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Internal architecture: Coarse; Immature
![](../pics/biopsy/fsh/fshcongnadh.jpg)
NADH stain
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![](../pics/biopsy/fsh/fshcongatp43.jpg)
ATPase pH 4.3 stain
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Immature muscle fibers
Type 2C: Intermediate color on ATPase pH 4.3
Alkaline phosphatase positive
Scattered; Small
![](../pics/biopsy/fsh/fshcongalp.jpg)
Alkaline phosphatase stain
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Endomysial cells
Histiocytic; Scattered
Common pattern with MHC-I upregulatioon by muscle fibers
![](../pics/biopsy/fsh/fshcongest.jpg)
Esterase stain
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MHC-1: Abnormal upregulation by muscle fibers
![](../pics/biopsy/fsh/fshcongmhc1.jpg)
MHC-1 stain
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FSHD, Congenital: Inflammation
4 year old female
![](../pics/biopsy/fsh/fshconghelp2.jpg)
H&E stain
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Inflammation (Childhood FSH): Lymphocytes in perimysium
![](../pics/biopsy/fsh/fshconghelp.jpg)
H&E stain
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![](../pics/biopsy/fsh/fshcongcells1.jpg)
H&E stain
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Inflammation: Lymphocytes around perimysial vessel
![](../pics/biopsy/fsh/fshcongcells2.jpg)
H&E stain
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FSHD: Early in course
![](../pics/biopsy/fsh/fshdearlyhe.jpg)
H&E stain
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FSH: Muscle Pathology
Muscle fibers
Sizes: Mild variation; Few small fibers
Endomysial capillaries
Large (Arrow; Above)
Misoriented (
Below): Often circumferential around muscle fibers
![](../pics/biopsy/fsh/fshhehypert.jpg)
H&E stain
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![](../pics/biopsy/fsh/fshdearlymhc1.jpg)
MHC1 stain
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FSH: Muscle Capillary Pathology
Endomysial Capillaries
Large
Misoriented: Often circumferential around muscle fibers
![](../pics/biopsy/fsh/fshmhc1capsearly.jpg)
MHC1 stain
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Control muscle
Capillaries: Most parallel to length of muscle fibers; Cut in cross-section
![](../pics/biopsy/fsh/mhc1cont.jpg)
MHC1 stain
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FSH dystrophy
2/4/2022