Immune Myopathies with Perimysial Pathology (IMPP): EJ antibody-associated
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Muscle fibers Perimysial pathology Also see IMPP Dermatomyositis: Adult, IMPP type Jo-1 muscle pathology |
EJ antibody: Perimysial pathology
 H&E stain |
Necrotic, Regenerating & Small muscle fibers: Common at edge of fascicles, near perimysium
Congo red stain |
 Gomori trichrome stain |
Necrotic, Regenerating & Small muscle fibers: Common at edge of fascicles, near perimysium
 VvG stain |
 H&E stain |
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 |
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
Perifascicular distribution: Fibers with cytoplasm stained for C5b-9 at edge of fascicle, near perimysium
 C5b-9 stain |
 MHC Class I stain |
 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
2/7/2020