Influenza A (H1N1) virus-associated pneumonia: high-resolution computed tomography-pathologic correlation

The purpose of this study was to describe the high-resolution computed tomography (HRCT) features of fatal cases of Influenza A (H1N1) virus-associated pneumonia and to correlate them with pathologic findings.

The study included six adult patients who died following Influenza A (H1N1) virus-associated pneumonia. All patients had undergone HRCT, and the images were retrospectively analyzed by two chest radiologists, who reached decisions by consensus. Two experienced lung pathologists reviewed all pathological specimens. The HRCT findings were correlated with the histopathologic data.

The predominant HRCT findings included areas of airspace consolidation (n=6) and ground-glass opacities (n=3). The main pathological features consisted of diffuse alveolar damage with hyaline membrane formation (n=5), associated with various degrees of pulmonary congestion, edema, hemorrhage, inflammatory infiltration and bronchiolitis. A patient who survived longer showed findings of organizing pneumonia.

Fatal cases of Influenza A (H1N1) virus-associated pneumonia can present as areas of consolidation on CT, with or without ground-glass opacities. These abnormalities can be pathologically correlated with diffuse alveolar damage. Patients with longer survival may present with findings of organizing pneumonia.