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Pathologic Findings in Novel Influenza A (H1N1) Virus (“Swine Flu”) Infection
Contrasting Clinical Manifestations and Lung Pathology in Two Fatal Cases

Sanjay Mukhopadhyay MD, Abraham T. Philip MD, Robert Stoppacher MD
DOI: http://dx.doi.org/10.1309/AJCPXY17SULQKSWK 380-387 First published online: 1 March 2010


Although novel influenza A (H1N1) virus infection has assumed pandemic proportions, there are few reports of the pathologic findings. Herein we describe the pathologic findings of novel influenza A (H1N1) infection based on findings in 2 autopsy cases. The first patient, a 36-year-old man, had flu-like symptoms; oseltamivir (Tamiflu) therapy was started 8 days after onset of symptoms, and he died on day 15 of his illness. At autopsy, the main finding was diffuse alveolar damage with extensive fresh intra-alveolar hemorrhage. The second patient, a 46-year-old woman with alcoholism, was found unresponsive in a basement and brought to the hospital intoxicated and confused. Her condition deteriorated rapidly, and she died 4 days after admission. The main autopsy finding was acute bronchopneumonia with gram-positive cocci, intermixed with diffuse alveolar damage. The pathologic findings in these contrasting cases of novel influenza A (H1N1) infection are similar to those previously described for seasonal influenza. The main pathologic abnormality in fatal cases is diffuse alveolar damage, but it may be overshadowed by an acute bacterial bronchopneumonia.

Key Words:
  • Novel influenza A virus
  • H1N1 virus
  • Swine flu
  • Autopsy
  • Fatal outcome
  • Lung pathology
  • Diffuse alveolar damage
  • Bronchopneumonia
  • Bacterial
  • Oseltamivir (Tamiflu)
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