Hyperhemolysis syndrome in sickle cell disease: case report (recurrent episode) and literature review.

BACKGROUND: Hyperhemolysis syndrome (HS) has been well described both in sickle cell disease (SCD) and non-SCD patients. The pathogenesis remains unclear. The possible mechanisms include bystander hemolysis, suppression of erythropoiesis, and destruction of red cells (RBCs) due to contact lysis via activated macrophages. CASE REPORT: This study reports a child with SCD who presented with recurrent episode of HS. In the first episode, the hemoglobin (Hb) level decreased to 4.1 g per dL. He was treated with intravenous immunoglobulin (IVIG) and oral steroids, and transfusion was avoided. Six months later he had another episode of HS. The nadir Hb level decreased to 3.2 g per dL, and further transfusions were given with IVIG-IV methylprednisolone cover.
RESULTS: RBC alloantibodies were not identified in pre- and posttransfusion samples in patient's serum in both episodes. HLA antibodies were also not detected.
CONCLUSION: This is the second reported case of recurrent HS in a child. Recent studies have shown that the adhesion molecules expressed on RBC erythroid precursor cells and reticulocytes can interact with macrophages and can cause hemolysis. Because RBC alloantibodies and HLA antibodies were not identified in this case, it is believed that the patient's cells and transfused cells were destroyed by macrophages either by direct contact lysis or by erythrophagocytosis. The possible mechanism of IVIG and steroids on suppression of macrophages resulting in cessation of hemolysis is discussed. Our case illustrates the danger of recurrent HS and the difficulty of balancing this against the need for transfusions in patients presented with severe hemolysis.