Diffuse alveolar damage

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Diffuse alveolar damage, abbreviated DAD, is a relatively common lung pathology that is grouped with the diffuse lung diseases and has several clinical correlates.

Diffuse alveolar damage
Diagnosis in short

Hyaline membranes. H&E stain.
LM dependent on phase - exudative: hyaline membranes; proliferative: interstitial thickening, inflammation (lymphocytes), type 2 pneumocyte hyperplasia, edema, Masson bodies in the airway, hyaline material (usu. focal); fibrotic: interstitial inflammation, interstitial fibrosis
Subtypes exudative, proliferative, fibrotic
LM DDx organizing pneumonia (especially for proliferative phase DAD), bronchiolitis obliterans
Site lung - see diffuse lung diseases
Prognosis often poor, dependent on severity and comorbidities
Other histologic correlate of: acute respiratory distress syndrome (ARDS), acute interstitial pneumonia (AIP), transfusion related acute lung injury (TRALI)
Treatment dependent on underlying cause

General

Etiology:

  • Abrupt hypoxemia with pulmonary infiltrates leading to epithelial cell and endothelial cell death not accompanied by cardiac failure.[1]

Classically, DAD is the histologic correlate of:

  • Acute respiratory distress syndrome (ARDS).
  • Acute interstitial pneumonia (AIP).

The DDx is broad:[2]

  • Infection/sepsis.
  • Toxic (smoke, oxygen).
  • Drug (amiodarone, chemotherapy).
  • Trauma/shock.
  • Inflammatory.
  • Idiopathic.

Notes:

  • DAD may not be present in all cases that are clinically ARDS.[3]
  • TRALI may have DAD; however, cases are reported without the pattern.[4]

Microscopic

Features:[5][6]

  1. Exudative:
    • Hyaline membranes - key feature.
      • Debris (pink crap) lines the alveolar spaces.
  2. Proliferative:
    • Interstitial thickening.
    • Inflammation (lymphocytes).
    • Hobnailing of alveolar lining cells (type 2 pneumocyte hyperplasia[7]).
    • Edema (link pink crap in the alveoli).
    • Masson bodies in the airway.
    • Hyaline material (usu. focal) - key feature.
  3. Fibrotic:
    • Interstitial inflammation.
    • Fibrosis.

DDx:[6]

Images

  • Exudative phase DAD - low mag. (WC/Nephron)

  • Exudative phase DAD - intermed. mag. (WC/Nephron)

  • Exudative phase DAD - high mag. (WC/Nephron)

  • Exudative phase DAD - very high mag. (WC/Nephron)

  • Exudative DAD (WC)

www:

See also

References

  1. ↑ Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 364. ISBN 978-1416054542.
  2. ↑ Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 91. ISBN 978-0781765275.
  3. ↑ "Comparison of the Berlin definition for acute respiratory distress syndrome with autopsy". Am J Respir Crit Care Med 187 (7): 761–7. April 2013. doi:10.1164/rccm.201211-1981OC. PMID 23370917.
  4. ↑ "Pulmonary pathology of rapidly fatal transfusion-related acute lung injury reveals minimal evidence of diffuse alveolar damage or alveolar granulocyte infiltration". Transfusion 48 (11): 2401–8. November 2008. doi:10.1111/j.1537-2995.2008.01879.x. PMID 18673344.
  5. ↑ Klatt, Edward C. (2006). Robbins and Cotran Atlas of Pathology (1st ed.). Saunders. pp. 103. ISBN 978-1416002741.
  6. ↑ 6.0 6.1 Castro, CY. (2006). "ARDS and diffuse alveolar damage: a pathologist's perspective.". Semin Thorac Cardiovasc Surg 18 (1): 13-9. doi:10.1053/j.semtcvs.2006.02.001. PMID 16766248.
  7. ↑ URL: http://d3jonline.tripod.com/20-Pulmonary_II/Pathology_of_Interstitial_Lung_Diseases.htm. Accessed on: 22 February 2012.
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