Severe post-thrombotic syndrome after iliac deep vein thrombosis in patients with iliac-femoral arteriovenous malformation.

We report seven cases of severe postthrombotic syndrome following deep vein thrombosis (DVT) complicated by iliac-femoral arteriovenous malformation. The patients' median age was 80 years (range, 70-88 years). All cases involved the left lower extremity, with a median onset of 2 years post-DVT. The CEAP classification was C6 in four cases and C4b in three. Treatment included compression therapy and transcatheter arterial embolization, with recent intractable ulcers treated by iliac vein stenting. These cases shared common features suggesting a distinct clinical entity: advanced-age onset, left iliac DVT triggered by immobilization, rapid progression to severe postthrombotic syndrome, and discovery of an asymptomatic arteriovenous malformation.