Pathologic features of lung biopsy specimens from influenza pneumonia cases.

Most histopathologic descriptions of influenza pneumonia are based on autopsy findings in fatal cases during epidemics and pandemics of influenza. We describe the histologic findings of influenza pneumonia observed in biopsy material derived from six sporadic cases of influenza (influenza A, four cases; influenza B, one case; and influenza A and B, one case). Four patients recovered completely, one patient died, and one was lost to follow-up. In addition to confirming previously published pathologic descriptions of influenza pneumonia, we also document a spectrum of less severe histologic findings with mild acute lung injury and bronchiolitis obliterans with organizing pneumonia.