Stanford School of Medicine

Surgical Pathology Criteria

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Acute Fibrinous and Organizing Pneumonia


  • Acute onset lung disease characterized by balls of fibrin filling alveoli

Alternate/Historical Names

  • AFOP

Diagnostic Criteria

  • Shares acute/subacute onset of symptoms with AIP/DAD
    • Age of onset 33-78
  • Patchy involvement rather than diffuse
    • Intervening lung is normal
  • Alveoli are filled with balls of fibrin
    • No hyaline membranes
  • Organization present in all cases
  • Mild to moderate interstitial lympho-plasmacytic interstitial infiltrate
  • Reactive pneumocyte hyperplasia
  • Vascular thrombi in some cases
  • Rapid progression in about half of patients with resultant death, similar to AIP
  • Has been proposed as a variant of AIP/DAD
  • Only one series (Beasley 2002) and a few case reports

Gerald J Berry MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting/updates: 11/20/10

Classification / Lists

Smoking Related Lung Diseases

Idiopathic Interstitial Lung Diseases

Other Diffuse Parenchymal Lung Diseases



  • Beasley MB, Franks TJ, Galvin JR, Gochuico B, Travis WD. Acute fibrinous and organizing pneumonia: a histological pattern of lung injury and possible variant  of diffuse alveolar damage. Arch Pathol Lab Med. 2002 Sep;126(9):1064-70.
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