Acute deep vein thrombosis (DVT) of the lower limbs in a 32-year-old man with chronic hypoplasia of the inferior vena cava (HIVC) without risk factors.

The anomalies of the inferior vena cava (IVC) have an incidence between 0.2 and 1 % in the general population [1]. The normal average diameter of the IVC is 17.5 mm (up to 25 mm maximum) and the spectrum of anatomical abnormalities of the IVC (e.g., absence or interruption of the vessel or variation in diameter) can be responsible for serious hemodynamic effects to the venous circulation of the lower limbs (i.e., venous stasis), and be a risk factor for the development of deep vein thrombosis (DVT). The association between hypoplasia of the IVC (HIVC) and DVT has been previously reported, even though the association of absence of the IVC and DVT is more frequently recorded [2]. Hypoplasia of the inferior vena cava should be taken into account when an unexplained DVT occurs in young patients, as DVT can occur in up to 5 % of young adults with IVC anomalies [3]. A 32-year-old man was referred to our Unit of Internal Medicine because of acute and intense back pain. History was unrevealing for risk factors related to venous disease, but the man had remained immobilised 3–4 days because of the intense pain. After admission, he underwent full (abdominal and pelvic) ultrasound examination, which revealed bilateral proximal (iliac–femoral veins) DVT (Fig. 1a, b; see Fig. 1c for comparison) and severe dilatation of the superficial venous circle of the lower limbs. Laboratory investigations for thrombophilic defects (including factor V Leiden, prothrombin G20210A, mutations A1298C and C8677T, proteins C and S and antithrombin III) were all negative. A computed tomography (CT scan) study of the superior abdomen showed hypoplasia of inferior vena cava (diameter 11 9 5 mm) along with bilateral thrombosis of the iliac and hypogastric veins; the right iliac vein was dilated and the paralumbar veins were hypertrophic; dilatation of the right hypogastric venous circle was present