[Difficulties in diagnosing an aortic arch thrombus]. / Difficultés diagnostiques d'un thrombus de la crosse aortique.

INTRODUCTION: Thrombosis of the aortic arch is a rare and often underdiagnosed source of peripherical arterial embolic events. EXEGESIS: We report a case with a non-typical initial clinical presentation of polyarteritis nodosa. A mobile thrombus in the aortic arch was secondarily suspected when disseminated arterial embolism appeared. Transthoracic echocardiography failed twice to diagnosticate the source of embolism. The diagnosis was only performed with transesophageal echocardiography and confirmed by computed tomography and magnetic resonance imaging of the thoracic aorta. The thrombus completely disappeared after six months of oral anticoagulant therapy. CONCLUSION: Although rare, this diagnosis mustn't be disregarded in an etiologic view of recurrent and disseminated peripherical ischemic events (even clinically silent ones) under penalty of detrimental functional consequences due to a delayed diagnosis.