Mediastinal extramedullary erythropoiesis in hereditary spherocytosis.

Evidence of thoracic extramedullary erythropoiesis has been noted before but it is considered rare in the course of chronic haemolytic anaemia. We report an adult who was admitted for splenectomy because of hereditary spherocytosis (HS). The evidence of a large mediastinal mass before surgery led us, after isotopic scanning using 111Indium transferrin, to suspect extramedullary erythropoiesis; this was confirmed by cytology during surgery. The utility of 111Indium transferrin as a bone marrow tracer is also noted.