Late-Onset Nonthrombotic Left Common Iliac Vein Compression Secondary to Degenerative Lumbar Disc: A Case Report of May-Thurner Variant.

May-Thurner syndrome (MTS) refers to venous outflow obstruction caused by extrinsic compression of the left common iliac vein (LCIV) by the overlying pulsatile right common iliac artery against lumbar vertebrae. The classic clinical presentation is acute unilateral left leg painful swelling due to deep venous thrombosis in a young woman in the second or third decade of life. We present a case of a 66-year-old woman who presented with late-onset left leg swelling caused by nonthrombotic venous hypertension due to degenerative lumbar disc bulge leading to LCIV compression against the left common iliac artery which was confirmed by computed tomography and intravascular ultrasound. Our case highlights the importance of high index of suspicion for MTS in elderly patients with unilateral leg swelling and the importance of multimodality imaging for understanding the mechanism and appropriate treatment of MTS.