Neuromuscular

NXP-2 Antibody: Regional Ischemic Immune Myopathy (RIIM)

Also see: RIIM pathology
Clusters of Necrotic & Regenerating Muscle Fibers
  Necrosis: Fibers in each cluster are in similar stages of necrosis or regeneration
  Anatomy: Clusters of damaged muscle fibers may not be at the very edge of fascicles
Perimysial Connective Tissue
  Wide
  Fragmented
  No immune cells

H & E stain


Congo red stain
Necrotic Muscle Fibers: Small cluster
  Necrotic fibers often have moderately dark, featureless cytoplasm with no visible myonuclei


C5b-9 complement stain
Necrotic Muscle Fibers
  Muscle fiber features
    C5b-9 staining of muscle fiber cytoplasm: diffuse
    NADH staining of cytoplasm is absent
  Anatomy
    Necrotic fibers are in clusters

NADH stain


NADH stain
Neighboring clusters: Necrotic (Left) & Regenerating (Right) Muscle fibers

Esterase stain

VvG stain
Neighboring clusters: Necrotic (Left) & Regenerating (Right) Muscle fibers

ATPase pH 9.4 stain


Alkaline phospohatase stain
Neighboring clusters: Necrotic (Above) & Regenerating (Below) Muscle fibers

ATPase pH 9.4 stain

Acid phosphatase stain


VvG stain
Clusters of Necrotic & Regenerating Muscle fibers: Distant from vascular bundle (Lower right)

Vessels
  Artery, Large (Left): Normal structure
  Artery, Small (Center): Abnormal wall structure
    Fibril (Elastin) layer: Incomplete (White arrow)
    Connective tissue inside fibril layer
  Vein (Right; White arrow)     Pale wall inside fibril layer
    No visible lumen

VvG stain

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10/20/2021