Acute autoimmune hemolytic anemia due to anti-En^a autoantibody successfully treated with rituximab

Autoimmune hemolytic anemia (AIHA) due to anti-En^a has been previously reported in association with massive intravascular hemolysis, disseminated intravascular coagulation, and fatal outcomes. Here we report a case of successfully treated AIHA due to anti-En^a .

A 69-year-old male with a past medical history of cirrhosis due to nonalcoholic steatohepatitis status post-orthotopic liver transplant presented with 1-month history of progressive anemia. At presentation, his hemoglobin (Hb) was 5.6 g/dL, hematocrit (Hct) 16%, reticulocytes 0.3%, direct bilirubin (bili) 4 g/dL, lactate dehydrogenase 533 units/L (reference, 125-220 units/L), and haptoglobin 254 mg/dL (reference, 40-273 mg/dL). Blood bank testing revealed an autoantibody present in his plasma and a direct antiglobulin test positive for immunoglobulin G (IgC) but negative for complement. He received 1 unit of an incompatible blood group O phenotypically matched red blood cell unit.

Over the course of the next 5 days, the Hb and Hct decreased to 4.1 g/dL and 12%, respectively, direct bili increased to 12.3 mg/day, reticulocytes slightly increased to 0.9%, and haptoglobin decreased to less than 8 mg/dL. Marrow study showed a hypercellular marrow with erythroid hyperplasia. Additional workup performed at a reference laboratory identified an anti-En^a autoantibody. He received prednisone and weekly rituximab infusions and was monitored weekly. At the 2-month visit, Hb and Hct were 10 g/dL and 32%, respectively.

Unlike two of the previously reported fatal cases of AIHA with anti-En^a specificity, this 69-year-old male treated with weekly rituximab infusion underwent clinical recovery and significant anemia improvement.