Neuromuscular

Eosinophilic Vasculitis

Axon loss
Granuloma
Muscle & Myopathy
Subperineurial edema
Vasculitic pathology
Wallerian degeneration

Vasculitic Pathology


H&E stain
Vessels
  Wall: Damaged; Cellular
  Lumen: Lost
Epineurium
  Eosinophils (Scattered) & other Cells
Nerve fascicle
  Subpoerineurial edema

Congo red stain


VvG stain
Vessels
  Wall: Damaged; Cellular; No fibrils
  Endothelial cells: Large
  Lumen: Lost


H&E stain
Vessels
  Wall: Damaged; Cellular; No fibrils
  Endothelial cells: Large
  Lumen: Lost

VvG stain


VvG stain
Vessels: Three types
  Within cell focus: No fibrils; Endothelial cells large
  Vein: No fibrils
  Vascular remnants: Clustered


Congo red stain
Inflammatory Cell Focus
  Contains scattered eosinophils

Gomori trichrome stain


VvG stain
Granuloma: Epineurial
  All cells in focus stain for acid phosphatase

Acid phosphatase stain

Acid phosphatase stain

Vasculopathy: Smaller Epineurial Vessels


VvG stain
Epineurial Vessels: Small
  Surrounded by: Cells; Pale epineurial connective tissue

H&E stain

Epineurial Vessel: Abnormal acid phosphatase stain inside fibrial layer
Perineurium around small nerve fascicle: Histiocytic cellularity
Epineurial connective tissue: Scattered histiocytic cells

Acid phosphatase stain

Fascicle Pathology: Subperineurial Edema


H&E stain
Subperineurial Edema
  Pale-stained region under Perineurium

Gomori trichrome stain

Eosinophils: Within area of subperineurial edema

H&E stain


Wallerian Degeneration


VvG stain
Wallerian Degeneration: Early
  Myelin sheath
    Pale; Vesicular; Irregular (Arrow, Above)
    Acid phosphatase stain (Below)
  See: Intramuscular nerve

Acid phosphatase stain

Wallerian Degeneration: Intramuscular Nerve

VvG stain

VvG stain
Wallerian Degeneration: Early
  Myelin sheath
    Pale; Vesicular; Irregular (Arrow, Above)
    Acid phosphatase stain (Below)

Acid phosphatase stain

Axon Loss
  Differential: Intrafasciclar
    More loss of large (Green) axons in some regions
    NCAM-stained Schwann cells: Empty (Red) without associated axons
  Active: Punctate or Irregular neurfilament staining

Neurofilament (Green) + NCAM (Red)

Axon Loss: Acute
  Loss of large axons within pale areas (Myelin)
  Punctate or Irregular neurofilament staining

Neurofilament stain

Axon Loss: Acute
  Regions of myelin abnormally express NCAM

NCAM stain


Neurofilament (Green) + MBP (Red)
Axon Loss: Acute
  Regions of myelin (MBP above or P0 below) have no axons

Neurofilament (Green) + P0 (Red)

Eosinophilic Vasculitis: Muscle features

Myopathy
Vasculitis


H&E stain
Histiocytic Vasculitis
  Vessel location: Perimysium
  Perivascular cells: Mostly histiocytes

H&E stain

Acid phosphatase stain
Histiocytic Vasculitis
  Vessel location: Perimysium
  Perivascular cells: Mostly histiocytes

Acid phosphatase stain

CD4 stain
Histiocytic Vasculitis
  Vessel location: Perimysium
  Perivascular cells: Often stain for CD4 & Mxa; Few stain for CD8

Mxa stain

CD8 stain

Eosinophilic Vasculitis: Myopathic features

H&E stain
Muscle Fibers
  Sizes: Moderately varied
  Internal nuclei: Some fibers

VvG stain


Acid phosphatase stain
Muscle Fibers: Internal Architecture
  Cytoplasmic aggregates
    Acid phosphatase positive (Above)
    Contain LC3 (Autophagy marker; Below)

LC3 stain


MHC Class I stain
Muscle fibers
  MHC1 upregulation
Perimysial vessels
  Irregular fragments without lumens (Below; Arrow)

MHC Class I stain

C5b-9 deposition
  Location: Connective tissue, Endomysial & Perimysial

C5b-9 stain


CD163 stain
Histiocytic markers
  CD163 histiocytes: Scattered in endomysium & perimysium (Above)
  HAM56: Unusual distribution on endomysium & around surface of muscle fibers (Below)

HAM56 stain

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11/3/2020