Right Atrial Thrombus After Cardiac Surgery With Tissue Expander in a Child With Right Pulmonary Agenesis

We report the case of a child with right pulmonary agenesis, congenital tracheal stenosis, and atrial septal defect (ASD). At age 2 years, an intrathoracic tissue expander was placed to reduce tracheal compression from mediastinal shift and to enable subsequent atrial septal defect closure. At age 5 years, a right atrial mass was incidentally detected along with right atrial compression caused by the expander. Emergency mass resection was performed, and the mass was diagnosed as a thrombus. The tissue expander was subsequently deflated and removed to prevent further compression. The patient had no recurrence of thrombus or respiratory symptoms during 8-year follow-up.