Fatal acute fibrinous and organizing pneumonia in an infant: The histopathologic variability of acute respiratory distress syndrome

Objective. The histopathologic pattern of acute fibrinous and organizing pneumonia (AFOP) has been described recently in cases of acute respiratory distress syndrome (ARDS) in adults and differs from the well-recognized pattern of classic diffuse alveolar damage (DAD). The objective of this study was to determine whether similar appearances can be seen in infant ARDS. Design: Case report and retrospective review of infant lung biopsies 1995-2005. Setting: Paediatric and neonatal intensive care units in a tertiary referral center. Patients: None. Interventions: None. Measurements and Main Results: A formerly premature infant with ARDS secondary to respiratory syncytial virus pneumonitis had histopathologic features of AFOP on open lung biopsy. Nine infants from 1995 to 2005 had definite histology of DAD or AFOP and fulfilled American-European Consensus Conference criteria for the diagnosis of ARDS. Of these, classic DAD findings were present in seven, whereas two had features of AFOP and DAD. Features suggesting viral infection were identified in five infants. Conclusions: The histopathologic features of AFOP may be seen in some cases of infant ARDS. The variability in the histopathology of ARDS raises questions as to the pathogenesis and clinical correlates of these different patterns.