RESUMO
Report of the case of a seventeen-year-old man in whom was discovered in the course of a systematic X-ray examination of the thorax a shadow of the right upper mediastinum. The variability of the pictures in relation with the upward or supine position, suggest the diagnosis of a vascular tumour, which was confirmed by angiocardiography. Towards the end of this examination there was a cardiac arrest with coma, which was suggestive of the probable diagnosis of thrombo-embolic accident, and the operation was undertaken under extracorporeal circulation. It made it possible to extract various recent clots and to perform a reconstitutive endo-aneurysmorrhaphy. The post-operative period was favourable, both from the neurological and haemodynamic points of view.