Thrombotic microangiopathy following allogeneic hematopoietic stem cell transplantation.

PURPOSE OF REVIEW The aim of this article is to assess the current understanding and uncertainties about the evaluation and management of thrombotic microangiopathy that occurs following allogeneic hematopoietic stem cell transplantation. RECENT FINDINGS Current data may not be sufficient to establish posttransplantation thrombotic microangiopathy as a discrete clinical or pathologic entity, distinct from other well recognized transplant-related complications. Analysis of case series of posttransplantation thrombotic microangiopathy illustrates uncertainties regarding incidence, risk factors, diagnosis, treatment, and survival. These studies have suggested the lack of efficacy of plasma exchange treatment and have identified other transplant-related complications, such as acute graft-versus-host disease and opportunistic infections, as the predominant causes of death in patients who had been diagnosed with posttransplantation thrombotic microangiopathy. Recently consensus diagnostic criteria were proposed by two independent groups to provide more uniform identification of patients with posttransplantation thrombotic microangiopathy; these criteria may result in a clearer definition of this syndrome. SUMMARY Posttransplantation thrombotic microangiopathy remains a diagnostic and therapeutic challenge. Further studies are required to determine if it is a specific entity and to define its relation to other transplant-related complications.