A Case of Coombs-Negative Primary Warm Autoimmune Hemolytic Anemia Due to IgA Antibody That Responded Well to Rituximab and Steroids.

Warm autoimmune hemolytic anemia (WAIHA) occurs due to antibodies active at body temperature that react with antigens on the surface of red blood cells, leading to hemolysis. Antibodies are typically IgG. WAIHA, associated exclusively with IgA antibodies, remains rare. Direct antiglobulin (Coombs) test may result negative in IgA antibody associated WAIHA. IgA-mediated WAIHA can present with severe hemolytic anemia. Further testing using an expanded direct antiglobulin test (DAT) panel is necessary to detect IgA antibodies if there is a high suspicion of autoimmune hemolytic anemia in cases that initially test negative for DAT. Steroids with or without rituximab are the mainstay of treatment. Early detection using an extended DAT panel with monospecific antisera helps avoid further investigations, unnecessary transfusions, and complications.