May-Thurner Syndrome: A Rare Case of Unilateral Deep Vein Thrombosis in an Elderly Woman.

BACKGROUND Deep vein thrombosis (DVT) is a critical disorder with a high incidence and a high disease burden. Multiple acquired and genetic factors leading to hypercoagulation, venous injury, and venous stasis account for its basic pathophysiology. One of the rarely considered underlying etiologies of DVT is May-Thurner Syndrome (MTS), also known as iliac vein compression syndrome. MTS is an anatomical variant in which the left common iliac vein is extrinsically compressed by the right common iliac artery against the lumbar spine, leading to the development of iliofemoral DVT. CASE REPORT We present the case of a 78-year-old woman who presented with chronic unilateral lower-extremity swelling and pain. Ultrasound was consistent with extensive DVT extending from the left common femoral vein to left popliteal vein. Further workup revealed left common iliac venous outflow obstruction due to the extrinsic compression by the overlying atherosclerotic calcified right common iliac artery crossing against the lumbosacral region. CONCLUSIONS MTS usually presents in the second to fourth decades of life, making it challenging to consider it as a differential diagnosis in older patients. The conventional treatment of DVT with anticoagulation alone is insufficient to address thrombotic MTS and can lead to recurrent DVT, post-thrombotic syndrome, and life-threatening complications. Our patient presented in the seventh decade of life, warranting a high index of clinical suspicion of MTS in patients presenting with unilateral leg DVT, regardless of patient age, for timely diagnosis and appropriate therapeutic management.