Infected teratoma of lower posterior mediastinum in a six-year-old boy.

A six-year old boy presented with prolonged unexplained fever caused by an infected teratoma of the lower posterior mediastinum. Modern imaging, combining ultrasonography with computed tomography, enabled the correct diagnosis of topography, extension and nature of this rare lesion to be made and explained the clinical features. Follow-up CT showed regression of the abscess after antibiotics thus permitting elective surgery.