Confluent hepatic fibrosis

Confluent hepatic fibrosis is a possible result of chronic injury to the liver, most commonly from cirrhosis or hepatic vascular injury.

Epidemiology

It most commonly occurs in patients with alcoholic cirrhosis (up to 15% of advanced cases), autoimmune hepatitis and primary sclerosing cholangitis ⁴.

Radiographic features

• confluent hepatic fibrosis occurs in the cirrhotic liver

• it occurs more frequently in the medial and anterior segments of the liver, mainly involving segments IV, VII, or VIII

• it is radiating from the porta hepatis to be widest at the capsular surface

• peripheral lesions appear partially wedge-shaped or concave-marginated abnormalities and are associated with mild capsular retraction

• delayed phase enhancement on CT and MRI due to the presence of fibrous tissue and lack of hepatocytes

CT

• wedge-shaped regions of hypoattenuation on non-contrast CT

• hypoattenuating on the arterial and portal venous phases

• fibrosis generally shows gradual enhancement

• trapped and crowded vessels may be seen within the lesion in 15% of cases

MRI

• wedge-shaped regions of moderate T2 hyperintensity due to edema

• T1 hypointensity (possible increased T1 signal from cholestasis)

• progressive postcontrast enhancement on the dynamic sequence but does not show enhancement on the delayed phase with hepatospecific contrast agents

• lack fat signal intensity

Confluent hepatic fibrosis is categorized as LR1 or LR2 in the LI-RADS classification system. If findings are indeterminate between fibrosis and hepatocellular carcinoma, it should be graded LR3 or LR4.

Differential diagnosis

The main differential diagnoses are:

• cholangiocarcinoma

  • most important differential due to lack of arterial hypervascularity and capsular retraction. But, peripheral type is generally more masslike

  • dilated intrahepatic bile ducts are also more common in cholangiocarcinoma than with confluent hepatic fibrosis

• infiltrative sclerosing hepatocellular carcinoma

  • minority of cases of confluent hepatic fibrosis (~15%) show arterial enhancement, so liver biopsy may be recommended to differentiate

  • confluent hepatic fibrosis shows progressive enhancement from arterial to delayed phase while HCC typically shows washout

  • may show pseudocapsule but not associated with volume loss or capsular retraction

• hepatic epithelioid hemangioendothelioma 

  • may show capsular retraction but otherwise has a different appearance and enhancement pattern

• segmental fatty liver

  • no capsular retraction and chemical shift MRI may be used to differentiate

• hepatic infarction

  • rare lesion that does not enhance even in the delayed phase