Neuromuscular

Macrophagic Myofasciitis (MMF)
Adult
  Histochemistry
Child
Aluminum
Ultrastructure

MMF: Adult


Gomori trichromestain
MMF: Cell Foci
  Location: Endomysium
  Cell features
    Large
    Abundant cytoplasm
    Contain: Aluminum (Morin stain); Inclusions
  Ultrastructure

VvG trichromestain

H&E stain
H&E stain

H&E stain
  • Cell foci & Infiltrates
    • Location: Endomysium > Perimysium.
    • Cells
    • Not granulomas
  • Muscle fibers
    • Not prominently affected.
    • No necrosis or regeneration.
  • Fascia (Perimysium): No necrosis

H&E stain
Nuclei: Large; Irregular shapes

Congo red stain
Cells in infiltrates   Mostly histiocytic
  Stain strongly with: Esterase & Acid phosphatase.

Esterase stain
Esterase stain

Esterase stain

Acid phosphatase stain
MMF cells:
  Confluent, strong acid phosphatase staining;
  Individual cell outlines in foci not visible

Acid phosphatase stain

VvG stain
MMF cells contain cytoplasmic lipid: Stains with VvG and Sudan

Sudan stain

PAS stain
Cells also stain moderately with PAS

MMF: Children


H&E stain

MMF: Lesions

  Locations: Perimysium & Endomysium
  Cells: Mostly large & Histiocytic; May contain sub-foci of non-histiocytic cells (Arrow)

H&E stain
H&E stain

H&E stain

MMF: Clusters of Histiocytic cells


VvG stain
MMF: Smaller lesion confined to perimysium

VvG stain

MMF: Vascularization

Cell foci often contain smaller vessels, some with thick basal lamina

VvG stain
Vessels in perimysial cell foci stain for Ulex

UEAI stain

Alkaline phosphatase stain
Vessels in cell foci stain for Alkaline phosphatase & ATPase

ATPase pH 9.4 stain

MMF: Cell Foci

  Large cells with abundant cytoplasm
  Location: Perimysium > Endomysium


H&E stain


H&E stain


H&E stain
MMF Cell Foci
  Large cells with abundant cytoplasm
  Location: Perimysium > Endomysium

Gomori trichrome stain

Congo red stain
MMF cells
  Cells: Large
  Nuclei: Large; Irregular shapes

VvG stain

Histiocytic cells

  Acid phosphatase positive
  Confluent staining


Acid phosphatase stain
Histiocytic cells:
  May extend from perimysium into endomysium

Acid phosphatase stain
Esterase stain
MMF cells in perimysium: Contain lipid
  Dark on Sudan
  Gray on VvG


Sudan black
VvG
MMF perimysial cells: May be PAS positive

PAS stain

MMF: MHC Class I

Cells in foci: Strong staining
Muscle fibers: Upregulation by morphologically normal fibers

MHC Class I stain

MMF: Cell Types



CD68 stain
Cells in foci: Strong staining for CD68

CD68 stain

CD3 stain
Cells in foci: Little staining for CD3 or CD20

CD20 stain

MMF: Aluminum stains


Morin stain

Morin stain

Quercetin stain

Quercetin stain

Macrophagic Myofasciitis: Aluminum-containing Histiocytes

Also see: IMAM


From: C Cai
Macrophages
  Contain inclusions: Spiculated; Electron dense (Typical of aluminum crystalloid)

From: C Cai

From: C Cai
Macrophages
  Contain inclusions: Spiculated; Electron dense (Typical of aluminum crystalloid)

From: C Cai
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11/30/2021