Severe vitamin B‐12 deficiency in a child mimicking thrombotic thrombocytopenic purpura

Abstract
We report a case of severe vitamin B‐12 deficiency in a child who had a clinical presentation of hemolysis and thrombocytopenia that suggested the diagnosis of thrombotic thrombocytopenic purpura (TTP) and was associated with decreased ADAMTS13 activity. In this report, we review vitamin B‐12 deficiency in children, the relationship between ADAMTS13 activity and TTP and discuss other conditions associated with decreased ADAMTS13 activity. Pediatr Blood Cancer 2009;52:420–422.