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Giant Cell Myositis ¹

Myopathy associated with Anaplastic Large Cell Lymphoma

General Giant Cells Myopathy Perimysium C5b-9 MRI ALCL

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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

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VvG stain

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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

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VvG stain

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

VvG stain

Alkaline phosphatase stain

Alkaline phosphatase stain

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Giant Cells

H&E stain

H&E stain

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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)

Congo Red stain

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Acid phosphatase stain

Giant Cells
  May occur in clusters

Acid phosphatase stain

Acid phosphatase stain

Giant Cells
  Acid phosphatase staining in central regions near nuclei

Acid phosphatase stain

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Esterase stain

Giant Cells
  Esterase diffusely stains cytoplasm of Giant cells

Esterase stain

Esterase stain

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Gomori trichrome stain

Giant Cells
Gomori trichrome stains cytoplasm of Giant cells red

Gomori trichrome stain

Gomori trichrome stain

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ATPase pH 4.3 stain

Giant Cells
  ATPase stains periphery of Giant cells

ATPase pH 4.3 stain

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NADH stain

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Giant Cell Myopathy

C_5b-9 Staining
  Perimysium
  Endomysial Capillaries

C5b-9 stain

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Giant Cell Myositis: MRI, Legs
  Patchy, varied involvement of muscles

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Anaplastic Large Cell Lymphoma: Muscle

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Characteristics

• Non-Hodgkin lymphoma, high grade
• Malignant proliferation of large & often bizarre lymphoid cells
• Cells: 2 types
  • Mononucleated
    • Cytoplasm: Prominent, Basophilic, Vacuolated
    • Nuclei: Eccentric, Multi-lobulated
    • Cell morphologic variants
      • Common
      • Lymphohistiocytic
      • Small cell
  • Multinucleated
    • Nuclear distribution: "Wraith-like"
    • Nucleoli: Prominent
• Molecular markers
  • CD30 (Cytokine receptor; Ki-1): 100%
    • Also present on: Hodgkin & Reed-Sternberg cells of classic Hodgkin disease
  • Epithelial membrane antigen (EMA): 75%
  • ALK expression: Some ALCL
    • ALK+
      • Males in the first three decades
      • Caused by chromosomal translocations: Most commonly t(2;5)
    • ALK-
      • Older patients
      • Poorer prognosis
      • Neoplasm: More pleomorphic cells
  • PAX5, Desmin & CD15: Negative (Positive in Hodgkin's lymphoma)
  • Lymphocyte phenotype: T-cell (60% to 70%); B-cell (10% to 20%); Null (10% to 30%)

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Clinical: ALCL

• Frequency: 3% of adult & 10% of childhood NHL
• Types
  • Primary systemic
    • Locations: Usually lymph nodes; Occasionally muscle
      • Extranodal features: Waldayer’s ring, skin, lung, bone, soft tissue, respiratory & GI
    • Muscle involvement: Rare
      • Mass: Most common
      • Rhabdomyolysis
      • Compartment syndrome
      • Pain
      • Source: May be dissemination or primary
      • Skeletal muscle lymphoma: Differential diagnosis
        • ALCL
        • Non-Hodgkin lymphoma: B- or T-cell
        • Large B-cell lymphoma
        • Marginal zone lymphoma
        • Follicle center cell lymphoma
  • Primary cutaneous
    • Sub-types: de novo; Extranodal spread
    • de novo: Indolent course

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Return to: Giant Cell Myositis
Return to: Neuromuscular Home Page

1. Intern Med 2019;58:277-282, Skeletal Radiol 2026;54:141-146

12/4/2024