Neuromuscular

Immune Myopathies with Perimysial Pathology (IMPP): EJ antibody-associated

Muscle fibers
Perimysial pathology

Also see
  IMPP
  Dermatomyositis: Adult, IMPP type
  Jo-1 muscle pathology


EJ antibody: Perimysial pathology


H&E stain
Perimysium: Fragmented, Irregular
Necrotic, Regenerating & Small muscle fibers: Common at edge of fascicles, near perimysium

Congo red stain

Gomori trichrome stain
Perimysium: Fragmented, Irregular
Necrotic, Regenerating & Small muscle fibers: Common at edge of fascicles, near perimysium

VvG stain


H&E stain
Perimysium
  Fragmented, Irregular
  Contains large cells with eosinophilic cytoplasm
Necrotic, Regenerating & Small muscle fibers
  Common at edge of fascicles, near perimysium

H&E stain

Perimysial cells: Large, irregularly-shaped nuclei

Congo red stain

Perimysial fragmentation

VvG stain


Acid phosphatase stain
Histiocytic (Acid phosphatase positive) cells
  Scattered in perimysium
  Phagocytosing & replacing necrotic muscle fibers

Acid phosphatase stain

Histiocytic (Esterase positive) cells
  Scattered in perimysium

Esterase stain

Perimysium: Abnormal alkaline phosphatase staining

Alkaline phosphatase stain

Perimysium
  Abnormal C5b-9 deposition
Endomysium
  Mild C5b-9 deposition

C5b-9 stain

EJ antibody: Muscle fibers


  Smaller, immature muscle fibers: Fibers with coarse internal architecture are more common near perimysium

NADH stain

Immature muscle fibers: Many small fibers, at edge of fascicle are type 2C (Intermediate stained)

ATPase pH 4.3 stain

Necrotic muscle fibers: Fibers with cytoplasm stained for C5b-9 at edge of fascicle, near perimysium

C5b-9 stain


MHC Class I stain
MHC Class I upregulation by muscle fibers: More prominent near perimysium

MHC Class I stain

Perifascicular muscle fibers: Cytochrome oxidase staining is normal

Cytochrome oxidase stain

Return to Inflammatory myopathies
Return to IMPP

References
1. Curr Opin Rheumatol 2011;23:595-604

3/28/2016