Benign Liver Lesions

Question 1

Benign liver lesions are present in what percentage of the population?

Answer 1

20%. Includes benign cysts.

Question 2

What is the most common benign liver tumor?

Answer 2

Hemangioma

Question 3

The most common presentation of a hemangioma?

Answer 3

Incidental finding. symptomatic hemangiomas are rare.

Question 4

Describe the Kasabach-Merritt syndrome.

Answer 4

Rare syndrome characterized by thrombocytopenia and DIC associated with giant hemangiomas. Usually “activated by unrelated surgery or dental procedure.

Question 5

Typical imaging characteristics of Hemangiomas?

Answer 5

Radiographic imaging is usually sufficient to diagnose these lesions.

– Non-con CT: Well defined, hypodense masses with areas of calcification & fibrosis. Occasional central scar

• • Contrast phase: peripheral nodular enhancement followed by progressive centripetal fill-in. This is pathognomonic.
• • large areas of contrast pooling in late phases are also characteristic.

Question 6

Is there a role for surgery with hemangiomas?

Answer 6

Only if symptomatic(bleeding). Risk of rupture is exceedingly small.

Question 7

What are the imaging characteristics of focal nodular hyperplasia (FNH) masses?

Answer 7

–Non-contrast CT: well defined margin and hypodense.

–Contrast phase: Homogenous & isoattenuated initially. Lesions are bright, hypervascular with the characteristic hypodense central scar on arterial phase. Ten minutes delay imaging shows uptake of contrast in central scar.

The above constellation of imaging characteristics is pathognomonic of FNH.

Question 8

The difference between hepatic adenomas and FNH are sometimes equivocal with imaging studies. Other than biopsy, how can these two entities be differentiated?

Answer 8

A nuclear medicine study called the sulfur colloid scan. Sulfur colloid scintigraphy demonstrates kuppfer cells in FNH(and normal liver). These cells are NOT present in hepatic adenomas.

Question 9

Once identified as FNH, how are these lesions managed?

Answer 9

–If assymptomatic - no treatment necessary. Some recommend 6month f/u US to rule out fibrolamellar variant HCC (Imaging characteristics between these two entities are identical).

• -If equivocal dx - biopsy vs. observation.
• -If uncertain or symptomatic - resection.

Question 10

A 28y/o female with a 12 year hx of OCP use presents with vague abdominal pain and a solid liver mass on abdominal U/S? What is the most likely diagnosis?

Answer 10

Hepatic adenoma. Definite female (11:1) predominance and highly associated with high estrogen states. With discontinuation of HRT, OCP’s or pregnancy - these lesions are known to regress significantly

Question 11

Do hepatic adenomas have a potential for malignant transformation?

Answer 11

Yes. There is a small, but definite risk of malignant transformation into HCC. This is perhaps 1-2% over a persons lifetime.

Question 12

Does FNH have malignant potential?

Answer 12

No

Question 13

What are the typical imaging characteristics of hepatic adenomas?

Answer 13

–These lesions usually appear heterogenous on CT scan with fat, areas of hemorrhage & necrosis present. MRI is often helpful to characterize.

– These lesions always reichly enhance with contrast. Typically there is NO central scar.

– Like hemangiomas, there is nodular peripheral enhancement with centripetal fill-in on CT.

Question 14

What is the typical management of hepatic adenomas?

Answer 14

In general, all should be resected. They have a significant risk of rupture, malignant transformation and it is difficult to differentiate from HCC especially when >5cm, with associated cirrhosis or large areas of necrosis.

Question 15

What malignant lesion may appear identical to FNH on CT imaging?

Answer 15

Fibrolamellar variant of HCC

Question 16

What age group is tyical for the fibrolamellar variant of HCC?

Answer 16

Typically occurs in the 2nd & 3rd decades of life. Almost universally in an otherwise normal liver (no cirrhosis).