Intrathoracic masses due to extramedullary hematopoiesis.

Extramedullary hematopoiesis often occurs in hemoglobinopathies, hemolytic anemias, leukemias, lymphomas, and myeloproliferative disorders. Liver, spleen, and lymph nodes are frequently involved. However, extramedullary hematopoiesis may also develop in other sites such as thymus, kidney, retroperitoneum, and paravertebral areas of the thorax. Extramedullary hematopoietic masses are often microscopic and asymptomatic, but sometimes they lead to tumor-like masses. We describe massive intrathoracic extramedullary hematopoiesis in a 41-year-old man with compound heterozygosis for beta-thalassemia and sickle cell anemia and functional asplenia. We also describe a 39-year-old man with beta-thalassemia intermedia, who was initially diagnosed as having tumor masses, but was later proved, by magnetic resonance imaging, to have extramedullary erythropoietic tissue. These observations provide further support to include extramedullary hematopoiesis among the differential diagnosis of tumor-like masses in patients with hematologic diseases.