AIP or ARDS? Not just semantics

A point that merits attention is the need to differentiate between ARDS and acute interstitial pneumonia (AIP). AIP is a rapidly progressive idiopathic interstitial pneumonia characterized by the presence of an organizing form of diffuse alveolar damage on histopathological examination of lung specimens. Although the histological pattern is indistinguishable from that found in ARDS, the term AIP is reserved for cases of unknown cause [2]. In fact, exclusion of a precipitating or etiological agent (which is usually identifiable in patients with ARDS) is one of the diagnostic criteria for AIP. The mortality from AIP is about 70% and is higher than that from ARDS [3].