Venous thromboembolism in a patient with an uncommon etiology of May-Thurner syndrome.

May-Thurner syndrome (MTS) consists of common iliac vein compression from an extrinsic source. Patients with MTS can present with a variety of symptoms, potentially making the diagnosis difficult. Classically, MTS will result in left iliac vein compression from the right iliac artery. In rare cases, it can be secondarily caused by compression from other anatomic structures in the pelvis. We present the case of a 43-year-old woman with MTS with iliofemoral deep vein thrombosis and pulmonary embolism caused by a large uterine leiomyoma. Our findings underscore the need to consider various etiologies of venous compression in patients with extensive unilateral venous thromboembolism.