[Thoracic localizations of extramedullary erythropoiesis]

A series of 8 patients affected with hemolytic beta thalassemia with intrathoracic extramedullary hematopoiesis is reviewed. All patients were studied with conventional radiologic techniques and with CT and MR imaging. There was good correlation between conventional radiology findings and MR and CT results. CT and MR imaging were useful to evaluate not only the topographic localization of the masses of extramedullary hematopoiesis, but also their functional status. On CT, masses in the active phase exhibit high density and marked enhancement after i.v. administration of contrast medium; in the remission phase, the masses are hypodense, due to fat substitution, and unenhanced. On MR images, the active phase is characterized by a relatively low signal in both T1 and T2, while in the remission phase high signal is observed in both T1 and T2. A sign is seen on MR images which is considered as pathognomonic: a peripheral ring with high signal. The use of CT and MR imaging allows detailed information on the evolution of the hemolytic disease to be obtained. These pieces of information cannot be obtained with conventional radiology, which allows, at any rate, the correct diagnosis to be made.