Intrathoracic extramedullary hematopoiesis simulating anterior mediastinal tumor.

Intrathoracic extramedullary hematopoiesis is a rare tumor occurring predominantly in the posterior mediastinum, most commonly in patients with congenital hemolytic anemias. The first reported case of this entity's occurring in the anterior mediastinum is described in a 68-year-old man with an incompletely characterized anemia. Definitive diagnosis was established only after median sternotomy and removal of the tumor.