INTRODUCTION
Autoimmune cytopenias are a rare but potentially life-threatening complication after hematopoietic stem cell transplant (HSCT). Autoimmune hemolytic anemia (AIHA) is the most common type of post-HSCT immune cytopenia and occurs when antibodies are directed against donor red blood cell antigens. The incidence of AIHA in the pediatric transplant population has been reported between 2.4-6%.[1-3] Given the rarity of post-transplant AIHA, guidelines for monitoring, management, and expected outcomes are not available.
Previously reported risk factors for the development of AIHA include unrelated donor use, conditioning regimens without total body irradiation, peripheral blood and cord blood transplants, non-malignant indication for transplant, and chronic graft-versus-host disease (GVHD).[4-7] Limited evidence suggests that variables within the immunologic landscape, including pre-determined factors such as pre-HSCT serotherapy and T cell depletion as well as post-HSCT factors such as B and T cell recovery, T cell mixed chimerism, and infectious complications, may contribute to the risk of AIHA.[3, 5, 8] The complexity and lack of comprehensive understanding of the pathophysiology of AIHA after HSCT makes treatment challenging, and there are low reported response rates to first line therapy with corticosteroids.[2, 9-11]
We performed a retrospective cohort analysis describing the incidence of post-transplant AIHA in pediatric patients undergoing HSCT at a tertiary care academic institution, characterizing current management strategies, and describing patient outcomes. We also performed a matched case-control analysis to compare outcomes of patients with AIHA to those without AIHA.