In IPF, anachronic and reiterative epithelial injury and loss of the alveolar-capillary integrity constitute the initial event and 'the point of no return' that trigger aberrant repair pathways leading to inappropriate, progressive, and heterogeneous lung scarring (UIP) [20] [21] [22] . DAD upon UIP might represent massive epithelial and endothelial injury of the lung areas yet preserved from Abstract Idiopathic pulmonary fi brosis (IPF) is a dreadful, chronic, and irreversibly progressive fi brosing disease leading to death in all patients aff ected, and IPF acute exacerbations constitute the most devastating complication during its clinical course. IPF exacerbations are subacute/acute, clinically signifi cant deteriorations of unidentifi able cause that usually transform the slow and more or less steady disease decline to the unexpected appearance of acute lung injury/acute respiratory distress syndrome (ALI/ARDS) ending in death. The histological picture is that of diff use alveolar damage (DAD), which is the tissue counterpart of ARDS, upon usual interstitial pneumonia, which is the tissue equivalent of IPF. ALI/ ARDS and acute interstitial pneumonia share with IPF exacerbations the tissue damage pattern of DAD. 'Treatment' with high-dose corticosteroids with or without an immunosuppressant proved ineff ective and represents the coup de grace for these patients. Provision of excellent supportive care and the search for and treatment of the 'underlying cause' remain the only options. IPF exacerbations require rapid decisions about when and whether to initiate mechanical support. Admission to an intensive care unit (ICU) is a particular clinical and ethical challenge because of the extremely poor outcome. Transplantation in the ICU setting often presents insurmountable diffi culties.