Neuromuscular

LGMD 2A: Calpain-3 deficiency

Child

Chronic myopathic changes
Immune features
Fiber types: Large 2 & 2C
Fat accumulation
Myopathic grouping
Necrosis
Regeneration
Splitting
Adult

Chronic myopathic changes
Myopathic grouping
Varied fiber size
Necrosis
Regeneration
Fiber types



LGMD 2A: Child


Myopathic changes


H&E stain

Myopathy
  Varied size of muscle fibers
  Split muscle fibers
  Increased endomysial connective tissue

H&E stain

Myopathic groups
  Clustered basophilic fibers (Arrow)



Muscle Fiber Splitting


H&E stain

Split muscle fiber (Arrow)
  Small fibers in region of split fiber are clustered

NADH stain
Split muscle fiber (Arrow)
  Split is highlighted by NADH stain
  "Splitting" is actually partial fusion

Muscle Fiber Necrosis


H&E stain
Pale muscle fiber (Arrow)
invaded by cells

Acid phosphatase stain
Acid phosphatase-stained cells
within pale necrotic muscle fibers

Muscle Fiber Types


ATPase, pH 9.4 stain
Most large fibers are Type 2

ATPase, pH 4.3 stain
Type 2C (intermediate staining) fibers are abundant

Immune features


H&E stain
Endomysial inflammation, minor

MHC Class I stain
Normal distribution of MHC Class I: Only on capillaries

Fat accumulation in perimysium


Sudan black stain

LGMD 2A: Adult


Myopathic changes: Variable involvement


H&E stain
Varied fiber size
Little necrosis or regeneration

H&E stain
Varied fiber size
Abundant necrosis and regeneration

Myopathic grouping

Large group of small basophilic
  muscle fibers with large nuclei


H&E stain

Small muscle fibers have coarse
  internal architecture


NADH stain

Small muscle fibers are type 2C
  with intermediate staining


ATPase, pH 4.3 stain
Small muscle fibers are immature
  with alkaline phosphatase staining


Alkaline phosphatase stain

Fiber types


ATPase, pH9.4 stain
Small & large size fiber populations contain type I & type II



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3/17/2015