Man with jaundice and abdominal distention.

Our appreciation is extended to Dr. Parin Bhayani, Indiana University Department of Radiology, for contributing this case.

Man with jaundice and abdominal distention.

Man with jaundice and abdominal distention.

Man with jaundice and abdominal distention.

Findings:

CT demonstrates a heterogenous and geographic region of hypo attenuation in the right hepatic lobe, no discrete masses are seen.  No mass effect, vessels are seen to course through this region of abnormality. 

US demonstrates increased hepatic echogenicity in the right hepatic lobe, no discrete masses.

MRI demonstrates the previously described abnormality in the right hepatic lobe to be consistent with focal fatty infiltration.  The in-phase and out-of-phase sequences show typical signal drop-out in this region.  There is no mass effect and no abnormal enhancement is identified.

• Focal fatty infiltration
• Not much else looks like it although CT findings could be worrisome for infiltrating malignancy

Man with jaundice and abdominal distention.

Key points: 

• Fatty infiltration (fatty change is the preferred term however) is a nonspecific response of hepatocytes to injury and toxins
  • Numerous causes including obesity, alcoholism, malnutrition, etc
• There are 2 distinct patterns of fatty changes in the liver
  • Diffuse fatty change – most common and involves the entire liver. Best demonstrated on non-enhanced CT by noting the liver density to be < 40 HU
  • Focal fatty change or focal fatty sparing – often produces some of the most confusing imaging findings on CT and can simulate a tumor
• Focal fatty change is important to differentiate from malignancy to avoid unnecessary further workup (including MRI and biopsy)
• Imaging characteristics
  • Geographic regions of hypo attenuation with density characteristic of fat. There may be interdigitating areas of normal liver parenchyma
  • No mass effect is a key finding – no bulging of liver contour or displacement of vessels
  • Angulated geometric boundaries between the involved and uninvolved liver parenchyma
  • US shows increased echogenicity in these regions but no discrete masses
  • MRI can be quite helpful but often unnecessary if the diagnosis can be made on the basis of CT and US
    • Signal drop-out when comparing the in-phase and out-of-phase sequences
    • No contrast enhancement

References: 

1. Federle, M. Steatosis (Fatty Liver). StatDx, Accessed 5/5/2011.
2. Brant, W. Liver, Biliary Tree, and Gallbladder. Fundamentals of Diagnostic Radiology. 3rd ed, pp 758 – 761.

Man with jaundice and abdominal distention.