Hepatic sinusoidal dilatation.

Hepatic sinusoidal dilatation refers to the enlargement of the hepatic capillaries. Most of the time this condition is caused by hepatic venous outflow obstruction, which results in vascular stasis and congestion of hepatic parenchyma. In this setting, hepatic sinusoidal dilatation can be related to pericardial disease, heart failure, compression or thrombosis of the hepatic veins or inferior vena cava (i.e., Budd-Chiari syndrome) or central veins/sinusoids involvement (i.e., sinusoidal obstruction syndrome). Nevertheless, some extrahepatic inflammatory conditions (such as pyelonephritis, cholecystitis, pneumonia, pancreatitis, intestinal bowel disease, and others) may be associated with hepatic sinusoidal dilatation without concurrent venous outflow obstruction. On contrast-enhanced cross-sectional imaging, hepatic sinusoidal dilatation is typically characterized by a mottled, reticular enhancement of the liver, usually referred to as "mosaic" pattern. Other hepatic and extrahepatic imaging features, such us the dilatation of the hepatic veins or the presence of ascites, can help in identifying the cause of sinusoidal dilatation.