Idiopathic pneumonia syndrome following hematopoietic stem cell transplantation.

Non-infectious lung injury following hematopoietic stem cell transplant may be driven by either immune or non-immune pathways of inflammation. Common alloimmune lung complications include idiopathic pneumonia syndrome (IPS), transfusion related lung injury, diffuse alveolar hemorrhage, and peri-engraftment respiratory distress syndrome, with both diffuse alveolar hemorrhage and peri-engraftment respiratory distress syndrome existing as subsets of IPS when infection is absent. This review will discuss the definitions, risk factors, and pathogeneses of IPS and highlight the diagnostic work-up and novel approaches to treatment.