[Hereditary hemorrhagic telangiectasia]

Hereditary hemorrhagic telangiectasia (HTT, or Osler-Weber-Rendu disease) is a constitutional vascular dysplasia characterized by hemorrhagic manifestations, cutaneous or mucosal telangiectases and visceral shunting due to arteriovenous malformations. In France, its prevalence varies from 1/6,000 to 1/8,500. The diagnosis is clinical and based on the common triad: chronic epistaxis, responsible for anemias, cutaneous or mucosal telangiectases (on typical locations) and the hereditary nature of these signs inheredited in an autosomal dominant way. Penetrance is almost complete at 50 years. Visceral complications produce highly variable manifestations: pulmonary arteriovenous malformations may be manifested by brain abscess or transient ischemic attacks, signs of chronic hypoxia or hemorrhagic rupture; neurological arteriovenous malformations can produce signs of compression or be hemorrhagic; hepatic arteriovenous malformations, which remain latent for a long time, become clinically severe in a limited proportion of patients; hemorrhagic, digestive arteriovenous malformations worsen chronic anemia. HHT is a genetic disorder; two genes (ALK1 and ENG) involved in the signaling pathway of the transforming growth factor-beta have been identified so far. Vascular homeostasis of capillaries is impaired, which leads to an accumulation in time of successive and progressive telangiectases and arteriovenous fistulas. Disease management consists in anemia management, as well as in epistaxis prevention and treatment. The management of arteriovenous malformations lies on early detection and the possibility to occlude them with interventional radiology.