Development of mixed-type autoimmune hemolytic anemia and Evans' syndrome following chicken pox infection in a case of low-titer cold agglutinin disease.

We describe a patient with low-titer cold agglutinin disease (CAD) who developed mixed-type autoimmune hemolytic anemia (AIHA) and idiopathic thrombocytopenia following chicken pox infection. At least 1 year before admission to hospital, the patient had mild hemolytic anemia associated with low-titer cold agglutinins. A severe hemolytic crisis and thrombocytopenia (Evans' syndrome) occurred several days after infection with chicken pox, and the patient was referred to our hospital. Serological findings revealed the presence of both cold agglutinins and warm-reactive autoantibodies against erythrocytes, and the diagnosis was mixed-type AIHA. Following steroid therapy, the hemoglobin (Hb) level and platelet count improved. The patient was closely followed over a 10-year period with recurrent documented hemolysis after viral or bacterial infections. Warm-reactive autoantibodies have not been detected in the last 2 years, and only the immunoglobulin M anti-I cold agglutinins with a low titer and wide thermal amplitude have remained unchanged. Therefore, the patient has received at least 10 mg prednisolone daily to maintain a Hb level of 10 g/dL. To the best of our knowledge, no adult case of low-titer CAD that has evolved into mixed-type AIHA and Evans' syndrome after chicken pox infection has been previously reported in the literature.