Neuromuscular

TYPE II MUSCLE FIBER ATROPHY

Clinical features
Childhood
Moderately severe
Early
Pathological features

Type II atrophy: Pathology


Type II Muscle Fiber Atrophy: Clinical associations


Type 2 Muscle Fiber Atrophy: Moderately Severe


H&E stain
Muscle fiber sizes
  Bimodal distribution
  Type 1 (Larger) muscle fibers are normal or somewhat small
Small muscle fibers
  Shape: Often angular; Some are elongated
  Distribution: May appear clustered

H&E stain

VvG stain

ATPase pH 9.4 stain
Small muscle fibers
  Usually Type 2 (Dark stained at ATPase pH 9.4)
  Shape: Often angular; Some are narrow and elongated
  Distribution: May appear clustered

ATPase pH 9.4 stain

ATPase pH 4.3 stain
Small muscle fibers: Type 2
  Pale stained at ATPase pH 4.6 & 4.3

ATPase pH 4.6 stain

NADH stain
Type 2 muscle fibers: Other stains
  NADH: Pale
  COX: Pale
  Esterase: Not dark

Esterase stain

PAS stain
Type 2 muscle fibers: Other stains
  PAS: Darker
  Phosphorylase: Darker

Phosphorylase stain

Type 2 Atrophy: Early


Congo red stain
Type 2 muscle fibers
  Elongated
  Narrow

H&E stain

Gomori trichrome stain
Type 2 muscle fibers
  Elongated
  Narrow

Congo red stain

ATPase pH 9.4 stain
Type 2 muscle fibers
  Shapes
    Elongated & Narrow
    Intermediate-sized & Polygonal

ATPase pH 9.4 stain
Type 2 muscle fibers
  Shapes
    Elongated; May wrap abound larger type 1 fibers
   
ATPase pH 9.4 stain
Type 2 Atrophy

ATPase pH 4.6 stain
Type IIB atrophy


ATPase pH 4.3 stain
Type 2 muscle fibers
  Small & Angular
  Pale stained with ATPase pH 4.3
  Smallest muscle fibers may be 2B (Intermediate stain with ATPase pH 4.6)

ATPase pH 4.6 stain

Childhood type II atrophy

Type 2 muscle fibers
  Small
  Polygonal or Round

H&E stain
Fiber size distribution: Bimodal, Large & Small
Small muscle fibers: Polygonal or Round

H&E stain

Gomori trichrome stain
Fiber size distribution: Bimodal, Large & Small
Small muscle fibers: Polygonal or Round

ATPase pH 9.4 stain
Fiber size distribution: Small muscle fibers dark stained (Type 2)
Small muscle fibers: Polygonal or Round

ATPase pH 9.4 stain

ATPase pH 9.4

ATPase pH 4.3 stain
Type 2 muscle fibers
  Pale stained
  Type 2A & 2B

ATPase pH 4.6 stain

NADH stain
Type 2 muscle fibers
  Pale on NADH, SDH & COX stain

Cytochrome oxidase (COX) stain

SDH stain

Type 2 muscle fibers
  Darker on PAS stain

PAS stain

See
  Fiber type disorders
  Fiber type properties

Return to Neuromuscular Home Page
Return to Myopathies with wasting

References
1. Am J Physiol Cell Physiol 2012; Online August
2. Am J Physiol Cell Physiol 2015;308:C932-943

7/18/2016