SPINAL MUSCULAR ATROPHY: Lower Extremity, Dominant

SMA-LED: Early pathology (2 year-old patient)

Denervation in muscle

H & E stain
Small & intermediate-sized angular & polygonal muscle fibers
Grouped muscle fiber atrophy
Hypertrophic muscle fibers
Internal nuclei

H & E stain

H & E stain

Inflammation: Mononuclear cells surround Intermediate-sized perimysial vessels

H & E stain

Muscle fibers: Intermediate-sized & Small; Polygonal, Angular or Very small, Rounded (Pyknotic clunps)

Esterase stain

Muscle fibers: Internal architecture

NADH stain
Large muscle fibers
  Coarse internal architecture
  Pale centers

Muscle: Fiber types

ATPase, pH 9.4
Large muscle fibers: Type 2 predominance

ATPase, pH 4.3

SMA-LED: Late stage muscle (22 years-old)

H & E stain

GT stain
End stage muscle
  Muscle fibers: Small, Rounded
  Endomysial connective tissue: Greatly increased
  Small muscle fibers: Esterase stained

Esterase stain

Muscle spindles: Preserved

H&E stain

H&E stain

Intramuscular nerve: Reduced staining on VvG

VvG stain

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