A very rare cause of low-back pain and sciatica: deep vein thrombosis due to absence of the inferior vena cava mimicking the clinical and radiological signs of lumbar disc herniation.

The authors report a very rare cause of low-back pain and sciatica in a patient with iliac vein thrombosis attributed to absence of the infrarenal segment of the inferior vena cava (IVC) with massively dilated venous collaterals draining via a paraspinal plexus into the azygous system. This 21-year-old man presented with acute low-back pain radiating to the left ventral thigh. The initial CT scan revealed an intraspinal lesion that mimicked lumbar disc herniation. Further clarification revealed an iliac vein thrombosis, which was triggered by the absence of the infrarenal segment of the IVC, a very rare vascular anomaly. Collateral venous return was developed and led to lumbar varicosities and epidural vein engorgements. Laboratory examinations revealed factor V mutation as a predisposing factor for thrombosis. The patient's symptoms were relieved with anticoagulation and antiinflammatory therapy. Absence of the infrarenal IVC associated with iliac vein thrombosis should be regarded as a very rare cause of radicular and low-back pain, and this condition can mimic the clinical and radiological signs of lumbar disc herniation. Sciatica might be the first clinical manifestation of this rare venous anomaly.