Left external iliac vein compression syndrome

Clinical History

35-year-old male patient presented with long-lasting symptoms of swelling in the left leg after a minor leg trauma 3 years ago. After an examination by a vascular surgeon a diagnosis of left leg venous insufficiency (CEAP stage 4) was suspected and the patient was referred for further imaging.

Imaging Findings

A Doppler ultrasound examination of the left leg arteries and veins was performed with normal findings in the arterial and deep venous system of the left leg. However, dilated superficial pudendal veins were observed on the anterior thigh. These communicated with the great saphenous vein (GSV) at the level of the upper thigh which was dilated through its entire course with varicose veins at the level of the knee. The varicose veins in the compartment of the GSV communicated with varicose veins of the dorsal calf in the compartment of the small saphenous vein (SSV) which was also dilated with signs of insufficiency.
Due to atypical findings on the Doppler examination, CT phlebography of the lower extremities was performed. A soft tissue mass measuring 52x40x74 mm was observed retroperitoneally at the level of the left external iliac vein, causing compression the lumen of the vein.

Discussion

Compression syndromes are rare diseases presenting with symptoms caused by congestion in which blood flow is obstructed via external compression [1]. The most common cause of iliac vein obstruction syndrome is compression of the left common iliac vein caused the left common iliac artery, also called May-Thurner syndrome [2]. However, the aetiology in this case was compression caused by a tumorous lesion, which was later histopathologically confirmed as a lipoma.

Venous compression syndromes present with symptoms of discomfort, pain and swelling in the drainage area of the corresponding vein which can be further complicated with thrombosis due to venous stasis [3]. It is also important to keep in mind accompanying signs and symptoms, such as weight loss or weakness, which can help with deducting the exact aetiology. However, these were not apparent in this case and with no significant medical history present, the suspicion of venous insufficiency was raised.

The imaging of choice in this case is Doppler ultrasound, which is fast, affordable, non-ionising and can easily depict vascular anatomy with superficial and deep venous thrombosis or insufficiency. The findings in this case were the insufficiency of the superficial veins of the left leg. They were accompanied by an insufficient perforator vein in the mid calf and edema of the left calf, but the key finding were dilated pudendal veins, which are not common in the case of superficial venous insufficiency of the leg and suggest the presence of collateral flow.
Finally, CT phlebography was recommended as the next diagnostic procedure. It can more precisely depict venous anatomy, along with corresponding findings in the soft tissues and bones. CT phlebography demonstrated a subtotal narrowing of the left external iliac vein and developed collateral flow via pudendal veins. The narrowing was caused by a retroperitoneal soft tissue mass with absorption coefficients of fatty tissues and the diagnosis of left external iliac vein compression syndrome caused by a lipoma was made.

Before CT, the vascular surgeon recommended wearing compression socks and the possibility of venous ablation therapy. However, after the CT examination, surgery was performed and the tumour extirpated after which complete decompression of the left EIV was achieved demonstrating how imaging completely changed therapy planning in this case report.

This case report demonstrated how important is to adequately assess all information gained from the patient and imaging findings in order to provide an accurate diagnosis and the best possible treatment for each patient.

Differential Diagnosis List

Final Diagnosis

External iliac vein compression syndrome

URL:	https://eurorad.org/case/15594
DOI:	10.1594/EURORAD/CASE.15594
ISSN:	1563-4086