Congenital hypoplasia of the inferior vena cava and inherited thrombophilia: rare associated risk factors for idiopathic deep vein thrombosis. A case report.

: In young patients, acquired and genetic causes of deep vein thrombosis frequently interact. The association of congenital hypoplasia of the inferior vena cava with antithrombin III deficiency has never been described in the literature as a causal factor of proximal deep vein thrombosis in young patients. We report the case of an 18-year-old patient affected by deep vein thrombosis due to this rare association without other common risk factors.