Phlegmasia cerulea dolens in a teenage boy found to have Factor V Leiden.

A 16-year-old boy with morbid obesity and asthma presented with 1 week of progressive right leg pain, swelling and discolouration that started 1 week after a minor fall. Ultrasound and then CT with contrast revealed a large occlusive deep venous thrombosis (DVT) extending from the calf through the inferior vena cava bifurcation. Heparin was initiated and catheter-directed thrombolysis with tissue plasminogen activator and balloon angioplasty were performed with good flow postprocedure, however, the clot reaccumulated after several days and the procedure had to be repeated. After this occurred twice more, finally a right common iliac and femoral vein stent was placed to prevent clot reaccumulation and vein stenosis. Hypercoagability testing revealed activated protein C resistance and genetic testing confirmed homozygous Factor V Leiden (FVL). Family history was significant for maternal lower extremity DVT at age 21 and possible DVT in the patient's maternal grandmother.