Thrombotic thrombocytopenic purpura‐hemolytic uremic syndrome following allogeneic HPC transplantation: a diagnostic dilemma

Abstract

BACKGROUND: Thrombotic thrombocytopenic purpura‐hemolytic uremic syndrome (TTP‐HUS) has been described as a specific sequela of allogeneic HPC transplantation (HPCT). Nevertheless, because multiple transplant‐related sequela can cause the characteristic clinical features of TTP‐HUS, the diagnosis is difficult. STUDY DESIGN AND METHODS: All English‐language articles describing patients with TTP‐HUS following HPCT were identified. Articles reporting five or more total patients, including at least one patient diagnosed with TTP‐HUS following allogeneic HPCT, were reviewed. All articles describing autopsies of patients diagnosed with TTP‐HUS following allogeneic HPCT were also reviewed. RESULTS: Thirty‐five articles reporting 5 or more total patients described 447 patients diagnosed with TTP‐HUS following allogeneic HPCT. The frequency of diagnosis of TTP‐HUS following allogeneic HPCT varied by 125‐fold (0.5%‐63.6%). Twenty‐eight different sets of diagnostic criteria were described in the 35 articles; 25 articles included both RBC fragmentation and increased serum LDH. Many risk factors described as correlating with the diagnosis of TTP‐HUS also predict greater risk for multiple transplant‐related complications. Benefit of plasma exchange treatment could not be documented. Survival information was reported for 379 patients, 232 (61%) died, and reported mortality rates varied from 0 to 100 percent. Autopsies have been reported for 35 patients who were diagnosed with TTP‐HUS following allogeneic HPCT; none had systemic thrombotic microangiopathy, the diagnostic abnormality of TTP‐HUS; and infection (19 patients) was the most commonly reported cause of death. CONCLUSIONS: The clinical features of TTP‐HUS following allogeneic HPCT may be caused by common transplant‐related complications; the benefit from plasma exchange treatment is uncertain.