Neuromuscular

NODULAR MYOSITIS

Case 1


Gomori Trichrome (GT); From S Ringel
Esterase
  • Granulomatous inflammation (Esterase positive regions) in perimysial connective tissue
  • Calcifications (Dark regions on GT stain)
  • Increased endomysial connective tissue in perifascicular regions
  • Small muscle fibers in a perifascicular distribution

Case 2


Gomori Trichrome (GT)
VvG
  • Varying severity of fiber loss and inflammation
  • Increased endomysial and width of perimysial connective tissue

Gomori Trichrome (GT)
VvG
  • Some areas have relatively mild muscle fiber involvement
  • There is endomysial and perimysial cellularity and widening

Gomori Trichrome (GT)
Gomori Trichrome (GT)
  • Some areas have alomost complete replacement of muscle fibers and perimysium by cells
  • Areas of "granuloma-like" cellularity (arrows), approximately the size of a muscle fiber, are present
  • On VvG (below), connective tissue in perimysium and vessels is lost but elastin fibrils (arrows) remain

VvG
VvG

Gomori Trichrome (GT)

"Granuloma-like" cellularity
Gomori Trichrome (GT)

Cells within the wall of an intermediate-sized vessel

VvG
VvG
Muscle fiber pathology
  • In some regions endomysial cells surround relatively intact muscle fibers (left)
  • Inflammatory cells may invade or replace muscle fibers (right)

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8/22/2005