Extramedullary hematopoiesis presenting as posterior mediastinal mass: a study of four cases.

We present four cases of extramedullary hematopoiesis occurring in the posterior mediastinum. The patients are two women and two men between the ages of 20 and 87 years. Two patients presented with a history of thalassemia, and one had a history of anemia of undetermined etiology. One patient was asymptomatic, and the posterior mediastinal mass was detected during a routine chest radiographs. Surgical resection of the mass was performed in one patient, whereas a biopsy was performed in the other three. Histologically, all the cases showed the typical features of extramedullary hematopoiesis, namely the presence of numerous lymphocytes admixed with megakaryocytes and red cell precursors. Follow-up information ranging from 2 mo to 3 years showed that all patients are alive and well.