transplant rejection




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  • Histology

    • acute rejection
      • perivascular, interstitial
      • mononuclear infiltrates
      • can have endothelialitis and lymphocytic bronchiolitis
    • chronic rejection
      • fibrosis, scarring of airways and vessels

  • Stains

    • trichrome for fibrosis

  • Adequacy

    • 5 pieces at least
    • well-expanded alveolated lung tissue
    • 3 levels at least

  • Grading

    • A: acute cellular rejection
      • 0 = none = no mononuclear infiltrate, hemorrhage or necrosis
      • 1 = minimal = scattered perivascular infiltrate (cuffing)
        • incomplete cuffing unlikely to be rejection
        • 2-3 cell thick, lymphoplasmacytic
        • no eosinophils or endothelialitis
      • 2 = mild = more perivascular infiltrates, eosinophils, endothelialitis, airway inflammation
      • 3 = moderate = extension of infiltrate to alveolar septa and airspaces
      • 4 = severe = prominent alveolar pneumocyte damage and endothelialitis, intraalveolar necrotic debris
    • B: airway inflammation: lymphocytic bronchiolitis
      • 0 = none = no evidence of bronchiolar inflammation
      • 1R = low grade = mononuclear cells in submucosa
      • 2R = high grade = epithelial damage (necrosis, metaplasia, intraepithelial lymphocytes), eosinophils, plasmacytoid cells
      • X = ungradable
    • C: chronic airway rejection - obliterative bronchiolitis
      • 0 = absent
      • 1 = present
    • D: chronic vascular rejection - fibrointimal thickening of vessels
      • only in wedge resections
    • AMR: controversial, no consensus
      • I: latent humoral response = circulating antibodies only
      • II: silent humoral response = C4d deposition
      • III: sub-clinical humoral rejection = tissue pathology
      • IV: humoral rejection = graft dysfunction
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