Résumé : Introduction Persistent left superior vena cava (PLSVC) is a rare vascular malformation, with several cases reported in the English literature. The diagnosis is made incidentally, during cardiovascular imaging or when a catheter is placed in the left jugular or subclavian vein. They are without associated hemodynamic alterations, except if they have left atrial drainage or an associated dilation of the coronary sinus. If necessary, long-term PSLVC catheterization with right atrial drainage is safe. Case Presentation We report the case of 40-year-old man, admitted for placement of totally implantable vascular access device (TIVAD) on the same day of his first chemotherapy. A disease localized to the right neck made it impossible to puncture on the right. During the puncture of the left internal jugular vein, the diagnosis of PLSVC was made. Postoperative investigations confirmed the diagnosis and showed the presence of the right superior vena cava to which it was connected by the left brachiocephalic vein. They also confirmed the drainage of PLSVC into the coronary sinus. In addition, they demonstrated the presence of an associated right aberrant subclavian artery of direct aortic origin. Chemotherapy was administered safely and the port was removed 9 months after insertion without any problem. Conclusion This is one of the rare cases reported in the English literature of PLSVC diagnosed during TIVAD insertion and the first to report an associated vascular malformation. We publish it to encourage physicians to think about this differential diagnosis and to carefully perform the appropriate investigations before using the port.