Hypoplasia of the inferior vena cava in a young man presenting with extensive deep venous thrombosis.

We present a case of a 34-year-old man with extensive deep venous thrombosis (DVT) who was found to have multiple abnormalities of venous anatomy, notably hypoplasia of the inferior vena cava with azygous continuation. DVT has an annual incidence of around 1 in 1000 people in the UK. Many cases will have readily identifiable risk factors, such as underlying malignancy, immobility or thrombophilia, but at times, these might not be so straightforward and unexpected contributing factors may be found. Although relatively uncommon in the general population, congenital venous abnormalities have been found at higher incidence in young adults presenting with spontaneous DVT and should therefore remain a consideration when classical risk factors are absent. 2015 BMJ Publishing Group Ltd.