What is extramedullary hematopoiesis?
Extramedullary hematopoiesis is caused by a proliferation of blood-forming elements in patients with thalassemia or other anemias and occurs most commonly in the liver and spleen and sometimes in the chest. On imaging, multiple lobulated masses along the thoracic spine or ribs may be seen with pressure erosions, often with associated osseous abnormalities and sometimes with associated splenomegaly. Fat attenuation or signal intensity components that are chronic may be visualized.