GCM

Giant Cell Myositis

General
Giant Cells
Myopathy
Perimysium
C_5b-9
MRI

H&E stain

Myopathy: Severe
Muscle fibers
Varied sizes
Immature fibers: Scattered
Endomysial connective tissue: Increased between muscle fibers
Giant cells
Large
Multinucleated
Locations
Scattered & Clustered
Perimysium & Endomysium
Granulomas: Not definite or None
Perimysium
Widened
Fragmented or Damaged: Some regions
Hypercellular: Including Multinucleated Giant cells
Alkaline Phosphatase: Strong staining

Congo Red stain

H&E stain

VvG stain

H&E stain

Myopathy: Severe
Muscle fibers
Varied sizes
Immature
Basophilic cytoplasm
Large myonuclei
2C fibers (Intermediate stain at ATPase pH 4.3)(Below)

ATPase pH 4.3 stain

VvG stain

Giant Cell Myopathy: Perimysial Connective Tissue
Wide
Cellular
Structure: Damaged
Granulomas
Alkaline Phosphatase staining

VvG stain

Alkaline phosphatase stain

Alkaline phosphatase stain

Giant Cells

H&E stain

H&E stain

Congo Red stain

Giant Cells
Langhans-Type: Nuclei in ring around priphery of cytoplasm (Above, Left)
Torton-type: Nuclei in center of cytoplasm (Above, Right)
Foreign Body-type: Nuclei scattered in cytoplasm (Below)