Huge cervico-thoracic thymic cyst.

We present a case of a 6 year-old boy who presented with a huge mass in the right side of the neck and changes its size with respiration and with straining. Computed tomography of the chest and neck showed a huge mass that was thought to be cystic hygroma. It was excised by both median sternotomy and a right cervical incision. Pathology revealed a thymic cyst.