Hepatocellular Adenomas

Hepatic / Hepatocellular adenomas are uncommon benign tumor commonly seen in young to middle aged women, with history of oral contraceptive use. 

👉 Hepatic adenomatosis:  >10 adenomas. Adenomas in hepatic adenomatosis is not related to the hormonal or other risk factors. They tend to be multiple, progressive, symptomatic, more likely to lead to hepatic dysfunction and possible malignant transformation. 

HCAs are now classified based on the genetic and pathologic subtypes as :

1. Inflammatory hepatocellular adenoma.
2. Hepatocyte-nuclear-factor-1-alpha (HNF-1α-mutated) hepatocellular adenoma. 
3. β-catenin-mutated hepatocellular adenomas.
4. Unclassified subtype (includes HCAs without any genetic abnormalities).

Typical hepatic adenomas show moderate arterial phase enhancement with washout in portal venous and delayed, appears isointense to rest of liver. Chemical shift imaging can produce loss of signal of the adenoma in out of phase images due to the presence of fat within.


Name two hepatocyte specific contrast agents?

1. Gd-BOPTA / Gadobenate Dimeglumine
2. Gadoxetate Sodium.

What will happen in case of HCA with hepatocyte specific contrast agents?
Ans : Will appear darker than rest of liver, as the hepatocytes in HCA are non-functional.

Easy to remember Hepatic Adenoma better as ‘Hepatocyte’ Adenoma, as it lacks biliary epithelium, portal vein and even Kupffer cells.

Incidence Ratio in Female to Male is 9:1, Why 

Ans: OCP use. (Anabolic steroids also increase the risk, common with young men).

Surgery is recommended irrespective of size, why?

1. Risk of rupture and shock.
2. Transformation into HCC.

Below MRI images are of a 25yr old female patient who presented with pain related to cholecystolithiasis. Three incidental slightly echogenic lesions are seen in both lobes during USG, for which MRI was suggested.

T2 weighted images showing slightly T2 hyperintense lesion in the superior subcapular portion of the left lobe, lateral segment. 

Another similar signal intensity lesion in right lobe, segment VII/VIII

The main lesion showing the signal intensity loss in the Out-phase images, suggesting intralesional microscopic fat content. No restricted diffusion were seen in these lesions. 

Subtlest of three in the superior portion of segment VII of right lobe, again showing the loss of signal intensity. 

Increasing the TE of T2 WI reduces the signal intensity of the lesion in addition to that of rest of the structures. (c.f. hemangioma shows similar signal on increasing TE). See this article to see how a hemangioma looks like on increasing TE ('The Light Bulb Sign')

  Dynamic post contrast images shows prompt arterial phase enhancement of the lesion (yellow arrow), and appearing someehat isointense to rest of liver in the further images.

References:

1. Luigi Grazioli, Lucio Olivetti, Giancarlo Mazza, Maria Pia Bondioni, "MR Imaging of Hepatocellular Adenomas and Differential Diagnosis Dilemma", International Journal of 
   Hepatology, vol. 2013, Article ID 374170, 20 pages, 2013.
2. Hepatocellular Adenomas: Correlation of MR Imaging Findings with Pathologic Subtype Classification, Radiology.
3. Hepatic Adenomas: Imaging and Pathologic Findings. Luigi Grazioli, Michael P. Federle, Giuseppe Brancatelli, Tomoaki Ichikawa, Lucio Olivetti, Arye Blachar, Radiographics.