Figure 5

Splenic extramedullary hematopoiesis in hemolytic–uremic syndrome. (a) H&E section illustrates immature-appearing myeloid and erythroid elements, similar to that seen in thrombotic thrombocytopenic purpura (× 500, oil immersion). (b) Myeloperoxidase confirms the myeloid nature of the immature cells (× 500, oil immersion). (c) No CD34 expression is seen in the infiltrate in hemolytic–uremic syndrome or thrombotic thrombocytopenic purpura (× 500, oil immersion).