Masson's vegetant intravascular hemangioendothelioma in an external jugular vein aneurysm with recurrent thrombosis.

A 50-year-old male patient was admitted for a symptomatic aneurysm of the external jugular vein. Thrombosis of the aneurysm was treated by oral anticoagulant but recurrence of neck swelling and thrombosis occurred 1 year after oral anticoagulant was discontinued. No other vascular anomalies were detected, and blood tests were normal. Surgical resection was done "en bloc" with the muscular fibers in contact. Pathologic examination was compatible with a Masson's vegetant intravascular hemangioendothelioma. To our knowledge, this is the first case of symptomatic Masson's vegetant intravascular hemangioendothelioma diagnosed in a patient with thrombosed aneurysm of a cervical vein.