We report the case of a 76-year-old man who presented with moderate active Crohn's colitis that was refractory to high-dose corticosteroids, mesalazine and 6-mercaptopurine. He subsequently received a trial of infliximab with poor response and was diagnosed with cytomegalovirus (CMV) colitis, improving on antiviral therapy. Three weeks into treatment he developed acute respiratory distress with hypoxaemia and diffuse pulmonary interstitial infiltrates. This was confirmed as 