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IPEX: Muscle pathology

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Immune dysregulation, Polyendocrinopathy, Enteropathy, X-linked (IPEX) syndrome

  ● Forkhead Box P3 (FOXP3) ; Chromosome Xp11.23: Recessive

• Epidemiology: Multiple families
• Genetics
  • Mutations: Missense & Deletion
  • Animal disorder: scurfy mouse
• FOXP3 protein
  • Transcription factor
  • Required for maintenance of thymus-derived regulatory T (tT_reg) cells
• Clinical
  • Onst age: < 1 year
  • Diarrhea: Intractable
  • Skin: Eczema; Atopy
  • Diabetes mellitus, Type I
  • Thyroid autoimmunity: Hypothyroid
  • Immune
    • Psoriatic Arthritis
    • Exaggerated responses to viral infections
  • Death: Infancy or Early childhood
• Laboratory
  • Hematologic
    • Hemolytic anemia
    • Thrombocytopenia
    • Eosinophilia
    • Hemophagocytic syndrome
  • Islets of Langerhans: Agenesis
  • Renal: Nephrotic syndrome
  • Serum IgE: High
  • Pathology
    • Infiltration of lymphoid & myeloid cells into multiple organs
    • Muscle
      • Inflammation
      • Muscle fibers: Necrosis & Regeneration
      • Perimysial connective tissue: Histiocytes; Structure damage
      • Vessels: Small vessels may have associated cells

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IPEX: Muscle Pathology

Inflammation Muscle fibers Perimysium Vessels

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H&E stain

Congo red stain

Perivascular cells: Around, and near, small perimysial vessels

VvG stain

H&E stain

Perivascular cells: Around small perimysial vessels

H&E stain

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Acid Phosphatase stain

Perivascular cells: Some are histiocytic
Perimysial cells cells: Large; Histiocytic

Acid Phosphatase stain

Esterase stain

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MHC Class I stain

MHC Class I
  Upregulation by muscle fibers in some regions
  Stains perimysial cells in some regions

MHC Class I stain

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Perimysial arteries & Veins
  Reduced staining for fibrils in vessel walls
  No inflammatory cells

VvG stain

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VvG stain

Perimysium
  Structure: Irregular; Fragmented
  Cells: Histiocytic; Some are perivascular

Acid Phosphatase stain

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Congo red stain

Muscle fibers: Immature
  Clustered
  Nuclei: Large
  Cytoplasm: Basophilic

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Gomori trichrome stain

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NADH stain

Muscle fibers: Immature
  Internal architecture: Irregular or coarse

NADH stain

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Muscle fibers
  Type 2C fibers: Scattered

ATPse pH 4.3 stain

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Muscle fibers
  No fiber type grouping

ATPse pH 9.4 stain

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1/7/2022