Neuromuscular

VASCULITIS

Axons
  Differential fascicular loss
Early lesion
Fibrinoid necrosis
Hemosiderin
Inflammation
  Other
Syphilis
Vessels
  Artery wall damage
  Granulomatous
  Intimal proliferation
  Large
  Normal
  Occluded
  Neovascularization
    Epineural
    Vessel Recanalization
Vein & Artery: Occluded
  Nerve showed: Differential fascicular loss of axons



VASCULITIC LESION: EARLY


H&E stain

Acid phosphatase stain

Acid phosphatase stain

FIBRINOID NECROSIS


H&E stain

H&E stain


VvG stain
Vasculitis
  Fibrinoid Necrosis: Thick orange layer in center of vessel
  Vessel wall
    Thickness: Increased
    Fibril layer: Irregular or Fibrils absent
  Epineurial connective tissue
    Neovascularization & Irregular structure: Surrounds vessel

VvG stain

Vasculitis
  Fibrinoid Necrosis: Blue-stained layer near lumen of vessel
  Vessel wall: Thickened
  Hemosiderin: In connective tissue around vessel

Alcian blue/Nuclear fast red

Vasculitis
  Fibrinoid Necrosis: Thick layer in center of vessel near lumen
  Vessel wall: Cellular; Reduced connective tissue

Toluidine blue stain

CONNECTIVE TISSUE (Perimysium or Epineurium) NEAR VESSELS

Alkaline phosphatase staining

Alkaline phosphatase stain

Alkaline phosphatase stain

Hemosiderin


NADH stain
Perimysial vessels: Surrounded by hemosiderin deposits in connective tissue

Congo red stain

Epineurium: Hemosiderin deposits; Neovascularization

Congo red stain

VASCULITIS: Occluded Vessels & Lumen pathology


H & E stain

H & E stain

H & E stain

VvG stain

Acid phosphatase stain


Gomori trichrome stain
Arteries: Varied degrees of occlusion
  Histiocytic Cells (Acid phosphatase positive)
    Locations: Artery wall & Surrounding connective tissue
  Lymphocytes: Less common
Connective tissue surrounding vessels
  Damaged & Rarified
  Contains histiocytic cells

Acid phosphatase stain

Arterial Damage
  Lumen: Occluded
  Fibril (elastin) layer: Damaged, Irregular (Arrow)

VvG stain

Perimysial arteriole: Occluded, Early neovascularization

VvG stain

Perimysial vessel: Occluded, Early neovascularization

Gomori trichrome stain

Vessel wall: Thickened around area of occlusion

Toluidine blue stain

Toluidine blue stain

VASCULITIS (Chronic): Neovascularization; Multiply recanalized Vessels


VvG stain

Gomori trichrome stain

H & E stain
Recanalization (Multiple lumens surrounded by endothelium) within intermediate-sized vessels with no elastin lamina

ATPase pH 4.3 stain

Gomori trichrome stain

NCAM stain

Elastin layer & fibrils: VvG stain

VvG stain
Artery: Damage
  Connective tissue & Neovascularization: Proliferation inside elastin layer
  Elastin layer: Incomplete in a region of vessel wall

VvG stain
A neighboring vein has normal wall structure



VvG stain
Occluded Artery
  Surrounding Connective Tissue: Irregular & Rarified (Above)
  Structure
    Elastin fibrils (Arrow): Reduced in number
    Central Connective tissue: Proliferation & Recanalization inside elastin layer

VvG stain


Alkaline phosphatase stain
Neovascularization
  New, small vessels within previous large vessel
  Endothelium of new vessels stains for alkaline phosphatase

Alkaline phosphatase stain


Acid phosphatase stain
Neovascularized vessel: Surrounded by scattered Hemosiderin globules (Arrow)

Neurofilament + Trichrome stain

VASCULITIS (Chronic & Ongoing): Epineurial neovascularization around Vessels

Differential diagnosis

H&E stain
Neovascularization: New small vessels in pale, hypercellular epineurial connective tissue around large vessels
Fibrinoid necrosis: Wide-stained region around vessel lumen

VvG stain


Congo Red stain
Epineurial connective tissue: Reorganized in region of neovascularization

VvG stain


Acid Phosphatase stain
Histiocytic cells: In Epineurium & Vessel walls


Alkaline Phosphatase stain
Epineurial Vessels & Connective tissue
  Vasculitic process involves connective tissue around vessel
  Alkaline phosphatase: Stains connective tissue around, & distant from, abnormal vessel


Gomori trichrome stain
Epineurial neovascularization
  Proliferation of small vessels in epineurium near larger vessel (Above)
  Many epineurial capillaries with endothelium stained by UEA-I (Below)

Ulex (UEA-I) stain


Toluidine blue stain
Epineurium
  Vessel: Abnormal structure
  Connective tissue: Neovascularization & Irregular structure

Endoneurial Microvessel Proliferation
  Unusual feature of vasculopathic neuropathies

Toluidine blue stain

Epineurial Vessel: Intimal Proliferation


H&E stain
Artery
  Lumen: Connective tissue proliferation

Congo red stain

Neurofilament stain
Artery
  Lumen: Connective tissue proliferation
  Elastic lamina: Damaged & Interrupted

NCAM stain

Acid phosphatase stain
Artery: Intimal proliferation

Gomori trichrome stain

VvG stain

Vasculitis
  Damaged Artery Walls: Abnormal fibril layer in
    Larger artery near nerve (Dark Arrow)
    Smaller epineurial artery (White Arrow)
  Axons
    Myelinated axons: Severe loss
    Unmyelinated, small axons: Relative preservation

VvG stain

Vasculitis: Larger artery
  Discontinuous fibril layer
  Intima proliferation

VvG stain

Vasculitis: Epineurial artery
  Abnormal fibril layer
  Intima proliferation

VvG stain

Vasculopathy: Larger artery with abnormal wall
  Fibril layer: Reduced number of fibrils
  Intima proliferation, Mild

VvG stain

Vasculitis: Axon loss
  Large axons: Near complete loss
  Small, unmyelinated axons: Relatively preserved

Neurofilament stain

Vasculitis
  Vessel wall: Contains blue mucinoid material inside elastin layer

Alcian blue/Nuclear fast red

Perivascular Inflammation


H&E stain
Vaaculitis: Inflammatory Cells
  Mixture of lymphocytes & histiocytes surrounds vessels

H&E stain

H&E stain

VASCULITIS: Other Inflammatory features


H & E stain

H & E stain
Inflammation patterns
  • Giant cells (Above Left; Arrow) or granulomas may be present
  • Inflammatory cells in vessel wall may be fragmented (Above Right)
  • Eosinophils may be present in cellularity around vessel (Below)

H&E stain
Fibrinoid necrosis: In vessel wall
Eosinophils: In perivascular inflammation


Differential fascicular involvement of nerve
  • Some fascicles have fewer axons than the others

Gomori trichrome stain

VvG stain


Vasculitis: Larger vessels


VvG stain
Vessel Wall Damage
  Elastin fibril lamina: Interrupted
  Intimal proliferation: Increased tissue inside fibril layer (See: Normal)

VvG stain

Abnormal cells in vessel wall

Acid phosphatase stain

Vasculitis: Endoneurium

ATPase stain reduced except onendoneurial vessels

ATPase pH 4.3 stain

Vessels: Intermediate-Sized

Normal
  Muscle
    Fetal
  Nerve
Immune Myopathies
  DM-VP
  RIIM
Vasculitis

Normal Vessels


Nerve: Epineurial Vein & Artery

Artery (Black arrow): Linear fibrils near lumen; Thick wall
Vein (White arrow): Interlaced, thin fibrils around outside of vessel; Thin wall

VvG stain

Epineurial Artery: Normal

Alcian blue stain

Epineurial Vein: Normal
  Vein wall contains less mucopolysaccharide than artery

Alcian blue stain

Muscle: Perimysial Vein & Artery


Artery (Top right): Linear fibrils near lumen; Thick wall
Vein (Bottom left): Interlaced, thin fibrils around outside of vessel; Thin wall

VvG stain

Muscle: Perimysial structural variations

  Vascular Perimysium: Contains intermediate sized arteries & veins
  Avascular Perimysium: Contains connective tissue & fibrils, but no vessels
    DM-VP: Muscle fiber atrophy is most often near avascular perimysium

Elastin
  Forms a continuous ring inside the smooth muscle layer: Most prominent in artery
  Is present in a network outside the smooth muscle layer: Artery & Vein
Vein (Bottom left) & Artery (Top right)

Smooth muscle actin (SMA) (Green) & Elastin (Red) stains

PECAM (Endothelium marker)
  Fibrils inside the smooth muscle layer: Most prominent in artery
Vein (Left) & Artery (Right)

Smooth muscle actin (SMA) (Red) & PECAM (Green) stains


Syphilitic arteritis


Oppenheim 1894

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10/17/2019