Teaching Case

A 47-year-old female was referred for CT evaluation of an asymptomatic mass in the left upper neck, as an initial ultrasound examination had revealed no abnormality. On physical examination a fluctuating mass was seen, which promptly disappeared on compression and enlarged considerably on Valsalva manoeuvre.

CT with 3D reconstruction confirmed saccular aneurysmal dilatation of the left internal jugular vein, with a maximum diameter of 2.46 x 1.86 cm (Fig 1-3). There was no evidence of thrombus in the aneurysm.

Venous aneurysm is a rare morphologic entity [1], most frequently described in children. In upper extremity and neck veins aneurysms are seldom reported as they are usually asymptomatic and without clinical relevance [2]. However, they should not be overlooked as they may result in significant symptoms including swelling, pain and emboli.
Ultrasound, CT and magnetic resonance imaging (MRI) have been utilised for morphological evaluation.
Ultrasound (US) combined with Doppler flow imaging is the first-line, non-invasive test of choice for the diagnosis of venous aneurysms by providing anatomic visualization as well as haemodynamic information.
On CT, appearances depend on the presence or absence of thrombosis within the aneurysm: the sac itself appears as a well-defined, round, slightly hyper attenuating lesion. Calcification may be present. Post-contrast a patent aneurysm appears bright with uniform enhancement. A thrombosed aneurysm demonstrates rim enhancement due to filling defect.
On MRI also, patent and thrombosed aneurysms display different imaging features: on T1 most patent aneurysms appear as flow voids, or may show heterogeneous signal intensity. In thrombosed aneurysms the appearance depends on the age of clot within the lumen. On T2 they are typically hypointense, and laminated thrombus may show a hyperintense rim.
The aetiology of IJVA is described as degeneration process [1, 3, 4]. Mechanical venous obstruction and congenital defects have been described in children [3, 5] and neurofibromatous venous invasion in adults.
Because of the low incidence of IJVA, treatment guidelines are not clearly established [6]. Given that IJVA remain asymptomatic in the majority of cases, and mural thrombosis is infrequently encountered, conservative treatment is recommended.