Hypertrophic area of liver that is surrounded by atrophic, fibrotic liver parenchyma and may at imaging have a bulging appearance.

LI-RADS Categorization:

• Observations thought to definitely represent hypertrophic pseudomasses should be categorized LR-1.
• Observations thought to probably represent hypertrophic pseudomasses should be categorized LR-2.
• Observations that are indeterminate for hypertrophic pseudomasses versus HCC should be categorized LR-3 or LR-4.

Comments:

• In comparison to surrounding more fibrotic liver, hypertrophic pseudomasses usually are
• mildly T1 hyperintense
• mildly T2 hypointense
• iso- or hypoenhanced in the delayed phase
• Hypertrophic pseudomasses may have greater fat deposition than surrounding liver
• Hypertrophic pseudomasses are seen more frequently in certain etiologies of cirrhosis (PSC, Budd Chiari, alcoholic liver disease) and cirrhosis complicated by chronic portal vein occlusion.

Pitfalls, Challenges, Differential DIagnosis:

• Hypertrophic pseudomasses need to be differentiated from expansile masses.
• Imaging features that favor hypertrophic pseudomass over expansile mass:
• Preserved hepatic architecture.
• Presence of undistorted vessels
• Multiplanar images (source or reformatted) may help correctly characterize observations as hypertrophic pseudomasses by showing preserved hepatic architecture and undistorted vessels.