Digestive organs' AVMS in HHT

Among the inherited vascular disorders, it has to be considered the hereditary hemorrhagic telangiectasia (HTT) or Osler-Weber-Rendu syndrome, a particular form of arteriovenous malformation (AVM), can affect different organs and systems: skin, oral mucosa, lips, brain, vertebrae, besides the digestive organs, such as stomach, small and large bowels and liver. Its histological base consists of abnormal telangiectatic vessels, which constitute atypical communications between arterioles and venules, instead of normal and well-developed capillaries. At histology, they have thin walls and are devoid of proper fibro-elastic and smooth muscular layers. This leads to an increased and precocious venous return and to a network of abnormal dilated vessels. The direct consequences of this pathology in the digestive hollow organs, stomach or intestine, are micro/macro hemorrhages. In the liver, different anomalies can follow such as an increased blood supply through enlarged arteries, portal hypertension, parenchyma fibrosis with dilatation of the biliary channels, and finally cirrhosis. As a general hemodynamic consequence, a right heart overload can follow. This syndrome can persist long-term in silence, or it can manifest with a chronic anemia or an acute upper or lower digestive hemorrhage. In case of hepatic involvement, the main clinical signs are represented by right upper abdominal pain, liver enlargement and dysfunction. The diagnosis is today based on corresponding endoscopic examinations, and, when affecting the hepatic parenchyma, on cross-sectional imaging, such as echography, CT and MR.