Hepatic adenoma - atoll sign

Case contributed by Matt A. Morgan
Diagnosis certain

Presentation

Patient with long history of oral contraceptive use presented for an ultrasound due to an elevated alkaline phosphatase level (US not shown). No other symptoms. This ultrasound revealed a liver lesion and CT was ordered for further characterisation.

Patient Data

Age: 45 years
Gender: Female

Initial CT study

ct
This study is a stack
Axial C+
arterial phase
This study is a stack
Axial C+ portal
venous phase
This study is a stack
Axial C+
delayed
This study is a stack
Coronal C+
arterial phase
This study is a stack
Coronal C+ portal
venous phase
This study is a stack
Coronal C+
delayed
Download
Info

There are no morphologic changes to suggest cirrhosis.

There are five hepatic lesions, three of which are best visualised on arterial phase imaging. All of these lesions demonstrate variable arterial enhancement.

The largest mass is in the subcapsular posterior segment of the right hepatic lobe (segment 7), measuring 3.6 x 5.6 x 4.4 cm. It shows heterogeneous diffuse patchy internal enhancement on the arterial phase with variable persistent enhancement on venous phase and is not discretely visualised on the delayed phase. The enhancement characteristics are not specific.

(The other lesions were thought to be a mix of classic and flash-filling haemangiomas)

FU MRI study with Eovist

mri
This study is a stack
Axial
T2
This study is a stack
Axial T2
- long TE
This study is a stack
Axial T2
fat sat
This study is a stack
Axial T2 fat
sat - long TE
This study is a stack
Axial T1
in-phase
This study is a stack
Axial T1
out-of-phase
This study is a stack
Axial
This study is a stack
Axial T1
C+ fat sat
This study is a stack
Axial T1 FS w
contrast PV phase
This study is a stack
Axial T1 FS w contrast
transitional phase
This study is a stack
Axial T1 FS w contrast
delayed phase
This study is a stack
Axial T1 FS w contrast
hepatobiliary phase
This study is a stack
Axial T1 FS w contrast
hepatobiliary phase
This study is a stack
Axial
DWI
This study is a stack
Axial
ADC
Download
Info

The liver is normal in size and configuration with multiple hepatic lesions again seen.

In the right posterior hepatic lobe there is a mass measuring 3.6 x 5.8 x 4.8 cm. It shows heterogeneous predominantly high T2 and intermediate T1 signal intensity as compared to the liver. It demonstrates focal regions of increased T1 signal intensity in the precontrast sequences, which may represent haemorrhagic foci. It also shows restricted diffusion with heterogeneous early arterial enhancement which remains hyperintense to liver parenchyma on portal venous sequences, and becomes heterogeneously hypointense to liver parenchyma on delayed and hepatobiliary sequences. Favour an inflammatory type hepatic adenoma.

(Three of the other lesions were found to be additional adenomas. One of them was a haemangioma.)

Atoll sign

mri
Download
Info

The yellow oval is around the thin T2 hyperintense border of this mass - a finding that has been associated with inflammatory hepatic adenoma subtype and termed the "atoll sign."

Case Discussion

The "atoll sign" - a rim of T2 hyperintensity around a liver mass that otherwise shows characteristics compatible with a hepatic adenoma - is associated with the inflammatory adenoma subtype.

After confident diagnosis that this was a hepatic adenoma as opposed to a malignancy it was effectively bland embolised due to its size and the risk of haemorrhage. It has shown no recurrence over the course of many years.

How to use cases

You can use Radiopaedia cases in a variety of ways to help you learn and teach.

Creating your own cases is easy.

:

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.