Neuromuscular

CHRONIC PARTIAL DENERVATION OF MUSCLE

Muscle
  Atrophic fibers
  Capillary pathology
  Fiber types
    Grouping
    Patterns
  Grouped atrophy
  Internal nuclei
  Necrotic & Clustered muscle fibers
  Pseudomyopathic changes
  Pyknotic nuclear clumps
  Split muscle fibers
Nerve
  Regenerating axon clusters

Groups (Size): Hypertrophic & Atrophic Muscle fibers



H & E stain
Large Muscle Fibers
  Distribution: Clustered
  Size: Often hypertrophied
Small Muscle Fibers
  Shape: Polygonal, Rounded or Nuclear Clumps
Endomysial connective tissue in regions of grouped muscle fiber atrophy
  Distribution: Clustered or Grouped
  Normal (Above) or Increased (Below)

H & E stain

Clusters, or groups, of large, intermediate & small sized muscle fibers

H & E stain
Grouped atrophy: Increased space between tiny muscle fibers

Gomori trichrome stain


VvG stain
Internal architecture: Hypertrophic muscle fibers have Irregular clear centers or Targets

NADH stain

Chronic Partial Denervation: Fiber type abnormalities
  Large fibers are commonly a single type: May be Type 1 or 2


ATPase pH 9.4 stain
Large muscle fibers: All type 1

ATPase pH 4.3 stain

Large muscle fibers: All type 2

ATPase pH 4.3 stain


ATPase pH 4.6 stain
Large, Type 2 muscle fibers: Abnormal
  Type 2C with varied degrees of intermediate staining on ATPase pH 4.6 stain (Above)
  Incomplete fiber type switch: Type 1 properties on COX stain (Below)

COX stain

Atrophic Muscle fibers

H&E stain

H&E stain

Gomori trichrome stain

Congo Red stain

Esterase stain

NADH stain

PYKNOTIC NUCLEAR CLUMPS


Also see
Pyknotic nuclear clumps: Morphology

H & E stain

H & E stain

 

H&E stain

Pyknotic nuclear clumps: High magnification

Congo red stain

Congo red stain

Pyknotic nuclear clumps: May also contain lipofuscin

H&E stain

Congo red stain

Pyknotic nuclear clumps: Grouped atrophy

H&E stain

H&E stain

Congo red stain

Pyknotic nuclear clumps: Stain dark with esterase & NADH

NADH stain

Esterase stain
Angular fibers: Esterase
Esterase stain

Pyknotic nuclear clumps: With lipofuscin

Acid phosphatase stain

Acid phosphatase stain

PSEUDOMYOPATHIC CHANGES


H&E stain

Gomori Trichrome stain
  • Endomysial connective tissue: Increased
  • Internal nuclei: One or several in muscle fibers
  • Pyknotic nuclear clumps
  • Grouped atrophy of muscle fibers
    • Groups are less well demarcated than in ongoing denervation
    • Increased endomysial connective tissue is especially prominent in these regions
  • Small muscle fibers may be rounded or angular
  • Hypertrophic muscle fibers: Common

SPLIT MUSCLE FIBERS

INTERNAL NUCLEI


H&E stain

NADH stain

H&E stain
  • "Split" muscle fibers probably result from partial fusion of regenerating fibers
  • These split muscle fibers are very large (hypertrophic)
  • Split muscle fibers often have internal nuclei

NECROTIC & CLUSTERED MUSCLE FIBERS


H&E stain
  • A hypertrophied muscle fiber may become necrotic (left)
  • Several different muscle fibers regenerate in its place and cluster within the old basal lamina


UEA I stain
Capillaries: Chronic Partial Denervation
  Increased numbers of capillaries adjacent to each muscle fiber
  Abnormal orientation: Some become circumferential around muscle fibers

UEA I stain

Return to Muscle biopsies
Return to Biopsy illustrations
Return to Neuromuscular home page
Return to Polyneuropathy Index

6/17/2017