Incidence and outcome of idiopathic pneumonia syndrome in pediatric stem cell transplant recipients

Idiopathic pneumonia syndrome (IPS) is a rare complication following stem cell transplant (SCT) and its incidence among pediatric SCT recipients is not known. To assess the incidence of IPS, we retrospectively reviewed the incidence of IPS at our center. IPS is defined as the presence of multilobar infiltrates by chest radiograph or computed tomography scan, need for supplemental oxygenation with declining pulse oximetry and no identifiable pulmonary infection. Between July 1999 and August 2005, 11 of 93 children who received a fully ablative allogeneic SCT (11.8%) developed IPS. All 11 patients had normal pulmonary evaluation before transplant. IPS developed at a median of 17 days (range 8-42 days) after transplant. Recipients of unrelated donor transplant had increased risk of developing IPS. There was a significant association between acute or hyperacute graft-versus-host disease (GVHD) and IPS (P=0.035). All patients had significant hypoxia and five patients required assisted ventilation. IPS was the cause of death in two patients. Although there was complete resolution of respiratory symptoms in the other nine patients, overall transplant-related mortality was significantly higher among patients with IPS (64 vs 17%, P=0.002). IPS is a relatively common complication in pediatric SCT recipients and acute GVHD is an important associated factor.