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Autopsy Findings in Eight Patients With Fatal H1N1 Influenza

Paul W. Harms MD, PhD, Lindsay A. Schmidt MD, Lauren B. Smith MD, Duane W. Newton PhD, Maria A. Pletneva MD, PhD, Laura L. Walters MD, PhD, Scott A. Tomlins MD, PhD, Amanda Fisher-Hubbard MD, Lena M. Napolitano MD, Pauline K. Park MD, Mila Blaivas MD, PhD, Joseph Fantone MD, Jeffrey L. Myers MD, Jeffrey M. Jentzen MD, PhD
DOI: http://dx.doi.org/10.1309/AJCP35KOZSAVNQZW 27-35 First published online: 1 July 2010


A novel H1N1 influenza A virus emerged in April 2009, and rapidly reached pandemic proportions. We report a retrospective observational case study of pathologic findings in 8 patients with fatal novel H1N1 infection at the University of Michigan Health Systems (Ann Arbor) compared with 8 age-, sex-, body mass index–, and treatment-matched control subjects. Diffuse alveolar damage (DAD) in acute and organizing phases affected all patients with influenza and was accompanied by acute bronchopneumonia in 6 patients. Organizing DAD with established fibrosis was present in 1 patient with preexisting granulomatous lung disease. Only 50% of control subjects had DAD. Peripheral pulmonary vascular thrombosis occurred in 5 of 8 patients with influenza and 3 of 8 control subjects. Cytophagocytosis was seen in all influenza-related cases. The autopsy findings in our patients with novel H1N1 influenza resemble other influenza virus infections with the exception of prominent thrombosis and hemophagocytosis. The possibility of hemophagocytic syndrome should be investigated in severely ill patients with H1N1 infection.

Key Words:
  • Influenza
  • H1N1
  • Autopsy
  • Diffuse alveolar damage
  • Hemophagocytosis
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