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SQSTM1: Distal Myopathy

Digenic: SQSTM1 c.1165 G>A; TIA1 N357S

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H&E stain

Chronic myopathy
Fiber sizes
  Varied from Small to Large, Occasional pyknotic nuclear clumps
  More small fibers in some areas than others
Perimysium & Endomysium: Replaced by fat
No necrosis or regeneration

H&E stain

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H&E stain

Small muscle fibers
May occur in clusters or groups
Some have basophilic cytoplasm & large nuclei
Irregular internal architecture or Dark staining

NADH stain

VvG stain

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Vacuoles

VvG stain

Vacuoles: Black-stained rim on VvG

VvG stain

VvG stain

Gomori trichrome stain

Gomori trichrome stain

Vacuoles: Red-stained rim on Gomori trichrome stain

Gomori trichrome stain

Gomori trichrome stain

Vacuoles: Red staining (? amyloid-like) on Congo red

Congo red stain

Congo red stain

Vacuoles: AMPDA granules

AMPDA stain

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Fiber types

ATPase pH 9.4 stain

Abnormal fiber types
Intermediate-stained muscle fibers at ATPase pH 4.3

ATPase pH 4.3 stain

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MHC Class I: Upregulated on muscle fiber surface

MHC Class I stain

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Esterase stain

Neuromuscular junctions

Esterase stain

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6/2/2021