Ectopic thymic tissue: A cause of emphysema in infants

Ectopic thymic tissue can present a diagnostic dilemma when it is located i n the posterior mediastinum. The diagnosis can be made by awareness of it a nd bq use of computed tomography (CT) and magnetic resonance imaging (MRI). Rarely, ectopic thymus are reported to cause airway obstruction. In infant s ectopic thymic tissue should also be considered in the differential diagn osis of secondary pneumonias and emphysema especially located in the upper lung zones. (C) Elsevier Science Inc., 1999.