A case of hemoglobin SC disease with cold agglutinin-induced hemolysis.

Children with sickle cell disease commonly require red blood cell (RBC) transfusion. We report the first case of hemoglobin (Hb) SC disease with development of severe anemia induced by cold agglutinin hemolysis after Mycoplasma infection. Complete blood count (CBC) showed falsely decreased RBC count and hematocrit and falsely elevated MCV and MCHC. Peripheral blood smear showed RBC clumping at room temperature; this disappeared after warming to 37 degrees C. Anti C3b-C3d was present on red cells, and indirect antiglobulin test revealed a circulating cold agglutinin. Furthermore, anti-Mycoplasma pneumoniae IgM antibody was detected in serum. Careful evaluation of CBCs and peripheral blood smears is required in cases of worsening anemia among sickle cell patients and consideration should be given to cold hemagglutinin disease as an etiology.