Usefulness of serum plasminogen activator inhibitor-1 for diagnosis and monitoring of late-onset sinusoidal obstruction syndrome after allogeneic stem cell transplantation

Sinusoidal obstruction syndrome (SOS) was originally defined as a clinical syndrome occurring by three weeks after transplantation; however, it occurs even after three or more weeks, and such cases are called late-onset SOS. We report here a case of late-onset SOS. The patient was a 17-year-old male with acute myeloid leukemia in second complete remission. He received a preparative regimen including busulfan followed by allo-peripheral blood stem cell transplantation from an HLA-matched sibling donor. On day 28 after transplantation, he developed hepatomegaly with pain. On day 33 PAI-1 level was increased. Two days later ascites developed, leading to a diagnosis of late-onset SOS. The symptoms improved with conservative therapy and the level of PAI-1 was normalized. When hepatic impairment appears three or more weeks after transplantation, late-onset SOS should be considered. PAI-1 is a useful marker for the diagnosis and follow up of late-onset SOS.