[Small liver vessels disorders].

Small liver vessels disorders are a heterogeneous group of rare diseases that can affect the portal venules, the hepatic sinusoids, the centri-lobular veins, or the hepatic arteries. The most frequent is the porto-sinusoidal vascular disorder (PSVD), which is characterised by damage of the portal venules or sinusoids and may be associated with portal hypertension, in the absence of cirrhosis. Diagnosis is therefore based on a liver biopsy. PSVD is often associated with an extrahepatic condition, most commonly immune-mediated, haematological, or a toxic. Its two main complications are variceal haemorrhage and portal vein thrombosis. The latter must be screened for by imaging every six months. Liver failure, on the other hand, is very rare in this context. It is therefore important to consider the diagnosis of PSVD when there is marked portal hypertension alongside preserved liver function or low liver stiffness, particularly in the absence of an obvious cause of cirrhosis or in the presence of an extrahepatic condition known to be associated with PSVD, as well as in cases of unexplained abnormalities of liver blood tests. The management of PSVD is like that of cirrhosis.