Neuromuscular

FOCAL MYOSITIS


H&E stain

H&E stain

H&E stain
Muscle morphology
  • Perimysium is markedly widened.
  • Perimysium is populated by large cells with surrounding clear area.
  • Necrosis & fragmentation of perimysium is not prominent vs. fasciitis


Perimysial pathology


H&E stain

Perimysium is invaded by inflammatory cells.



H&E stain
Some areas of connective tissue are sworled or disrupted.



H&E stain

H&E stain

H&E stain
Endomysial pathology
  • Muscle fibers have varied size. Small fibers are rounded.
  • Edema may be present between muscle fibers.
  • Some mononuclear inflammation can occur(Right).



Alkaline phosphatase stain

Acid phosphatase stain
Immune & Inflammation
  • Alkaline phosphatase strongly stains perimysium & endomysium.
  • Acid phosphatase staining cells in the perimysium
    are less common than in fasciitis (Right).



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12/4/2012