Neuromuscular

MYH7 disorders

Childhood
Gowers-Laing: Adult

Gowers-Laing: Adult

 Muscle fiber sizes
  Varied: Small to Hypertrophied
  Bimodal distribution

H & E stain

H & E stain
Small muscle fibers
  Often present in clusters
  May be intermediate sized or very small
  May be round, polygonal or angular

H & E stain

H & E stain
Small muscle fibers
  Varied shapes & sizes

Gomori trichrome stain

Gomori trichrome stain
Fiber sizes
  Varied
  Bimodal distribution

VvG stain

NADH stain
Small muscle fibers
  Stain dark with NADH: Likely type I

NADH stain

NADH stain
Cores
  In some muscle fibers within a group of type I fibers
  Other fibers have irregular internal architecture

NADH stain

ATPase pH 4.3 stain
Fiber types: Grouped

ATPase pH 4.3 stain
Small muscle fibers: Most are type I (Dark stained)

ATPase pH 4.3 stain

ATPase pH 9.4 stain
Type I muscle fibers (Pale stained)
  May be large or small
  May be present in groups or clusters

ATPase pH 9.4 stain
Serial sections with different stains

ATPase pH 4.3 stain

ATPase pH 9.4 stain

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

PAS stain

Cytochrome oxidase stain

MYH7 mutation: Childhood


H&E stain
Fiber sizes
  Varied
  Bimodal distribution

Congo red stain
Muscle fiber internal architecture
  Irregular
  "Smudged" regions with reduced staining

Gomori trichrome stain

NADH stain
Muscle fiber internal architecture
  May be coarse with variable dark & light-stained areas
  Core-like pathology: Minicores; Eccentric cores

NADH stain
Muscle fiber internal architecture
  Reduced mitochondrial staining in some areas

Cytochrome oxidase stain

ATPase pH 9.4 stain
Muscle fiber types
  Type 2, especially 2B, fibers tens to be smaller than type 1

ATPase pH 4.3 stain

ATPase pH 4.6 stain
Neuromuscular junctions
  Large & Dark stained for esterase

Esterase stain
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11/14/2021