Hemophagocytic Lymphohistiocytosis (Macrophage Activation Syndrome)

Gomori trichrome stain
Necrotic muscle fibers
  Dark-stained or Pale
  Some are associated with cells

H&E stain

H&E stain
Necrotic muscle fibers
    Dark-stained (Below) or Pale (Above)

H&E stain


Progressive phagocytosis of muscle fibers (from their outside) by large multinucleated cells.
Muscle fibers are necrotic with a hyaline appearance.

H&E stain

Congo red stain
Progressive phagocytosis of muscle fibers by large multinucleated cells.

NADH stain
Multinucleated phagocytic cells may be NADH positive.
Necrotic muscle fibers are pale and have lost NADH staining.

Alkaline phosphatase stain
Alkaline phosphatase: Hemophagocytic cells stain black.

Acid phosphatase stain
Myophagocytic cells (red) progressively phagocytose & replace muscle fibers..

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