ABSTRACT
A 66-year-old man was admitted with distal edema of his right leg. He had undergone radical prostatectomy and pelvic lymphadenectomy for prostatic cancer 23 days previously. Abdominal computed tomography (CT) showed a lymphocyst (4.5 x 3.0 cm) along the right pelvic wall compressing the right external iliac vein. CT with contrast medium showed thrombus formation (about 9 cm) in the distal portion of the right external iliac vein and femoral vein. An inferior vena cava filter was placed to prevent pulmonary embolism, and anticoagulation with warfarin was started. One week later, CT showed shrinkage of the lymphocyst and thrombus in the vein, as well as a large thrombus trapped in the filter. Follow-up CT taken 2 months later revealed marked reduction of the lymphocyst and absence of thrombus in both the vein and filter. A lymphocyst, also known as a lymphocele, is a complication of radical pelvic surgery. Most lymphocysts are asymptomatic and regress spontaneously, but may lead to deep vein thrombosis and pulmonary embolism, usually a few weeks after surgery. Careful observation is needed even after discharge from hospital.