Pulmonary extramedullary hematopoiesis.

Extramedullary hematopoiesis (EMH) is the formation and development of blood cells outside of the bone marrow. Of particular interest to chest physicians and radiologists is the occurrence of EMH in the lungs and pleura. There have been several reports of patients presenting with pulmonary EMH published in the literature and the majority are due to a secondary process, such as myeloproliferative disorders, hemolytic anemias, hereditary spherocytosis, and Gaucher disease.