[Venous aneurysm of V. saphena accessoria--a case report].

A 43-year-old male was admitted for subcutaneous mass of rt. inguinal lesion. Saccular dilatation of vein is a rare phenomenon and usually termed "venous aneurysm". Venous aneurysm has been reported in the following vein: face, neck, extremities, superior vena cava region, portal vein region and by-pass grafting vein. This is the 1st report of a venous aneurysm found in V. saphena accessories in Japan. The true etiology is unknown, but underlying causes which produce damage to the venous wall (trauma, inflammation, congenital weakness, and localized degenerative change) have been mentioned as possible causes. Rarely, thrombosed venous aneurysm may cause pulmonary emboli. Definitive diagnosis is established by venography. Venous aneurysm often increases or reduces in size according to the change of venous pressure by proximal vein compression postural change and Valsalva maneuver. In general, surgical resection of the aneurysm is the treatment of choice.