Neuromuscular

FASCIITIS

Immune
Toxic

Fasciitis: Immune


H&E stain
H&E stain
Muscle & Connective tissue pathology
  • Lesions
    • Location: Perimysium & Epimysium (not shown)
  • Perimysium
    • Fragmented & Pale
    • Cellular & Widened in some regions
  • Neighboring muscle fibers: Relatively unaffected.

Acid phosphatase stain
MHC Class I
  Perimysium: Mild staining
  Muscle fibers: Most are normal; Mild increase in some muscle fibers near perimysium
  Capillaries, endomysial: Normal staining

MHC Class I stain
C5b-9 Deposition
  Perimysium: Moderate staining
  Endomysium: Diffuse deposition

MHC Class I stain

H&E stain
Acid phosphatase stain
Inflammation
  • Cells in regions of perimysial damage
    • Large nuclei & Pink cytoplasm
    • Histiocytic (Acid phosphatase & Esterase positive)
  • Occasional regions of undamaged perimysium contain lymphocyte infiltrates (Right).

H&E stain
H&E stain

Fasciitis: MRI

Fasciitis: MRI

Multiple regions of increased T2 signal in leg muscles (L > R)

Fasciitis: Toxic, Eosinophilic

H&E stain
Perimysiun: Damaged structure & cellularity with little involvement of adjacent muscle fibers

VvG stain

Acid phosphatase stain
Histiocytic cells: In perimysial connective tissue

Esterase stain

Esterase stain

H&E stain
H&E stain

H&E stain
Perimysial connective tissue pathology: Fragmented & Hypercontracted

VvG stain

Congo red stain
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6/10/2020