Acute extrahepatic infectious or inflammatory diseases are a cause of transient mosaic pattern on CT and MR imaging related to sinusoidal dilatation of the liver

Purpose: To report the association of a mosaic enhancement pattern on contrast-enhanced CT or MR imaging and hepatic sinusoidal dilatation (SD) with acute inflammatory conditions affecting extrahepatic organs. Methods: From 2007 to 2012, patients with acute inflammatory diseases who underwent contrast-enhanced CT and/or MRI of the liver with a mosaic enhancement pattern were selected. Clinico-biological and other imaging features were collected at diagnosis and during follow-up. Results: Sixteen patients were included (15 women, median age 27 years; range 18–68). Five women (33 %) were receiving oral contraceptives. Acute inflammatory diseases included pyelonephritis (n = 10), pancreatitis (n = 2), pneumonia (n = 1), septicemia (n = 1), active Crohn's disease (n = 1), and infectious colitis (n = 1). Median white blood cell count was 13,250 cells/μL (range 11,500-18,000 cells/μL) and CRP level 94 mg/L (range 60–121 mg/L). Mosaic enhancement pattern was present in the whole liver and was prominent in the subcapsular areas. Four patients underwent liver biopsy confirming SD. Eleven patients underwent follow-up imaging showing normalized aspect in 9/11 patients after a median of 2 months. Conclusion: Acute diseases of extrahepatic organs, associated with a marked systemic inflammatory syndrome should be added to the list of conditions causing a reversible hepatic sinusoidal dilatation as manifested by a mosaic enhancement pattern on contrast-enhanced CT or MR imaging. Key Points: • Acute extrahepatic infectious/inflammatory diseases are a cause of transient MP. • In most patients, MP was seen during both arterial and portal venous phase. • In all patients, the mosaic enhancement pattern was diffuse, but more conspicuous in subcapsular areas. • MP was no longer seen after resolution of the acute disease. • No liver biopsy should be performed.