Figure 1
Unenhanced abdominal CT
Heterogeneous isodense mass at the segment VI of the liver.
Inflammatory hepatocellular adenoma - CT and MRI findings
SectionAbdominal imaging
Case TypeClinical Cases
AuthorsDaniel Ramos Andrade, Yessica Costa, Luís Curvo Semedo, Cristina Marques, Filipe Caseiro Alves
Connected authors
43 years, female
Clinical History
A previously healthy 43-year-old woman presented at the emergency room with abdominal pain for some months. Physical examination revealed a mass at the right flank. Blood work was unremarkable.
Imaging Findings
Abdominal CT revealed a 5.2 cm well circumscribed liver mass, which was heterogeneous but predominantly isodense with the liver parenchyma on unenhanced images (Fig. 1). After intravenous contrast administration, slight enhancement of the peripheral parts of the tumour with central areas of hypoattenuation was seen. On delayed images, there was persistent enhancement of the mass (Fig. 2-4).
The patient underwent an abdominal MR to better clarify these aspects.
On T1-weighted images the lesion showed an isointense signal (Fig. 5) and was hyperintense on T2-weighted images (Fig. 7). On both sequences it presented a hypointense central area (Fig. 5, 7). There was no signal loss from the in-phase to the out-of-phase sequence (Fig. 5, 6). After intravenous administration of gadolinium-ethoxibenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA), the mass presented with arterial enhancement, with delayed washout and hypointensity in the hepatocellular phase (Fig. 8-11). Diffusion weighted imaging revealed slight restricted diffusion with intermediate signal on the ADC map (Fig. 12, 13).
The patient underwent an abdominal MR to better clarify these aspects.
On T1-weighted images the lesion showed an isointense signal (Fig. 5) and was hyperintense on T2-weighted images (Fig. 7). On both sequences it presented a hypointense central area (Fig. 5, 7). There was no signal loss from the in-phase to the out-of-phase sequence (Fig. 5, 6). After intravenous administration of gadolinium-ethoxibenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA), the mass presented with arterial enhancement, with delayed washout and hypointensity in the hepatocellular phase (Fig. 8-11). Diffusion weighted imaging revealed slight restricted diffusion with intermediate signal on the ADC map (Fig. 12, 13).
Discussion
Surgery revealed a soft brown subcapsular mass. Microscopically it was heterogeneous, constituted by hepatocytes in a trabecular pattern with large cytoplasm and regular nucleus, surrounded by inflammatory infiltrates, sinusoidal dilatation and congestion, mimicking hepatic peliosis. Some cells showed immunoreactivity to serum amyloid A.
These findings were diagnostic of the inflammatory subtype of hepatocellular adenoma.
Adenomas are rare benign liver tumours, consisting of sheets of normal-appearing hepatocytes but with distorted acinar architecture. They most commonly occur in young/middle-aged women and have a strong correlation with oral contraceptives. They can be complicated by rupture and undergo malignant transformation. [1, 2]
Clinically, they may be asymptomatic or manifest with a palpable mass, fever, leukocytosis or rupture with haemorrhage.
Recent studies have categorized three distinct genetic and pathologic subtypes. [3]
The most frequent is the inflammatory subtype which, at pathologic examination shows inflammatory infiltrates, sinusoidal dilatation and peliosis.
This last characteristic may be the reason the central part of our mass was hypointense in both T1 and T2-weighted MR sequences and why it did not enhance. This subtype of adenoma is typically hyperintense on T2-weighted images, with a higher signal at the periphery because of the dilated sinusoids. On T1-weighted sequences, it can be iso to hyperintense, with no signal drop-off on out-of-phase images, which means there are no significant intracellular fat deposits. After gadolinium administration, there is intense arterial enhancement which persists during the portal and delayed phases. [2, 4] No enhancement is usually seen in the hepatocellular phase with Gd-EOB-DTPA, which helps in the differential diagnosis with focal nodular hyperplasia (FNH) - which is typically iso or hyperintense. [5]
The hypointense central area of the lesion could have easily been misdiagnosed as a central scar and so the diagnosis of fibrolamellar hepatocarcinoma or focal nodular hyperplasia could also have been considered. The scar of fibrolamellar hepatocarcinoma is frequently calcified while the scar of FNH is hyperintense on T2-weighted images and shows delayed enhancement. [1]
CT findings of adenomas are nonspecific. They are usually heterogeneous, with moderate enhancement during the arterial and portal phases, with the degree of enhancement being slightly less than with FNH. [1]
MR is the imaging tool of choice for subtype characterization of hepatocellular adenomas. Intense T2 hyperintensity associated with delayed persistent enhancement has very high sensitivity (85%) and specificity (87%) for the diagnosis of inflammatory adenomas. [4]
Lesions bigger than 5 cm are prone to rupture, so surgical resection is advised, which was the case in our patient. [4]
These findings were diagnostic of the inflammatory subtype of hepatocellular adenoma.
Adenomas are rare benign liver tumours, consisting of sheets of normal-appearing hepatocytes but with distorted acinar architecture. They most commonly occur in young/middle-aged women and have a strong correlation with oral contraceptives. They can be complicated by rupture and undergo malignant transformation. [1, 2]
Clinically, they may be asymptomatic or manifest with a palpable mass, fever, leukocytosis or rupture with haemorrhage.
Recent studies have categorized three distinct genetic and pathologic subtypes. [3]
The most frequent is the inflammatory subtype which, at pathologic examination shows inflammatory infiltrates, sinusoidal dilatation and peliosis.
This last characteristic may be the reason the central part of our mass was hypointense in both T1 and T2-weighted MR sequences and why it did not enhance. This subtype of adenoma is typically hyperintense on T2-weighted images, with a higher signal at the periphery because of the dilated sinusoids. On T1-weighted sequences, it can be iso to hyperintense, with no signal drop-off on out-of-phase images, which means there are no significant intracellular fat deposits. After gadolinium administration, there is intense arterial enhancement which persists during the portal and delayed phases. [2, 4] No enhancement is usually seen in the hepatocellular phase with Gd-EOB-DTPA, which helps in the differential diagnosis with focal nodular hyperplasia (FNH) - which is typically iso or hyperintense. [5]
The hypointense central area of the lesion could have easily been misdiagnosed as a central scar and so the diagnosis of fibrolamellar hepatocarcinoma or focal nodular hyperplasia could also have been considered. The scar of fibrolamellar hepatocarcinoma is frequently calcified while the scar of FNH is hyperintense on T2-weighted images and shows delayed enhancement. [1]
CT findings of adenomas are nonspecific. They are usually heterogeneous, with moderate enhancement during the arterial and portal phases, with the degree of enhancement being slightly less than with FNH. [1]
MR is the imaging tool of choice for subtype characterization of hepatocellular adenomas. Intense T2 hyperintensity associated with delayed persistent enhancement has very high sensitivity (85%) and specificity (87%) for the diagnosis of inflammatory adenomas. [4]
Lesions bigger than 5 cm are prone to rupture, so surgical resection is advised, which was the case in our patient. [4]
Differential Diagnosis List
Hepatocellular adenoma, inflammatory subtype
Focal nodular hyperplasia
Fibrolamellar hepatocellular carcinoma
Final Diagnosis
Hepatocellular adenoma, inflammatory subtype
References
[1] Lee J, Sagel SS, Stanley RJ, Heiken JP (2006) Computed Body Tomography with MRI Correlation. Lippincott Williams & Wilkins Vol 1 - chapter 12
[2] van Aalten SM, Thomeer MG, Terkivatan T, Dwarkasing RS, Verheij J, de Man RA, Ijzermans JN (2011) Hepatocellular adenomas: correlation of MR imaging findings with pathologic subtype classification. Radiology Oct;261(1):172-81. doi: 10.1148/radiol.11110023. (PMID: 21875850)
[3] Bioulac-Sage P, Rebouissou S, Thomas C, Blanc JF, Saric J, Sa Cunha A, Rullier A, Cubel G, Couchy G, Imbeaud S, Balabaud C,Zucman-Rossi J (2007) Hepatocellular adenoma subtype classification using molecular markers and immunohistochemistry. Hepatology Sep;46(3):740-8 (PMID: 17663417)
[4] Katabathina VS, Menias CO, Shanbhogue AK, Jagirdar J, Paspulati RM, Prasad SR. (2011) Genetics and imaging of hepatocellular adenomas: 2011 update. Radiographics 31(6):1529-43. doi: 10.1148/rg.316115527 (PMID: 21997980)
[5] Campos JT, Sirlin CB, Choi JY (2012) Focal hepatic lesions in Gd-EOB-DTPA enhanced MRI: the atlas. Insights Imaging Oct;3(5):451-74. doi: 10.1007/s13244-012-0179-7 (PMID: 22700119)
Case information
| URL: | https://www.eurorad.org/case/11885 |
| DOI: | 10.1594/EURORAD/CASE.11885 |
| ISSN: | 1563-4086 |
Figure 2
Post-contrast arterial phase abdominal CT
Mild heterogeneous enhancement of the liver mass. Central parts of the mass do not enhance.
Figure 3
Post-contrast portal venous phase abdominal CT
Moderate enhancement is still seen except for central hypoattenuating areas.
Figure 4
Post-contrast equilibrium phase abdominal CT
There is persistent enhancement of the mass in this delayed phase.
Figure 5
In-phase T1-weighted abdominal MR
Isointensity of the mass to the rest of the liver. The central part is hypointense.
Figure 6
Out-of-phase T1-weighted abdominal MR
There is no signal loss from the in-phase to the out-of-phase sequence.
Figure 7
Fat saturated T2-weighted abdominal MR
Hyperintensity of the periphery of the mass.
The central part is hypointense.
Figure 8
Arterial phase T1-weighted abdominal MR (Gd-EOB-DTPA)
Intense enhancement of the liver mass. The central part does not enhance.
Figure 9
Portal venous phase T1-weighted abdominal MR (Gd-EOB-DTPA)
There is still enhancement of the peripheral parts of the lesion.
Figure 10
Equilibrium phase T1-weighted abdominal MR (Gd-EOB-DTPA)
Washout of the lesion is seen at this phase.
Figure 11
Hepatocellular phase T1-weighted abdominal MR (Gd-EOB-DTPA)
Hypointensity of the lesion is well appreciated in this phase.
Figure 12
Diffusion weighted imaging (b=700)
The mass shows restricted diffusion
Figure 13
Apparent diffusion coefficient map
Intermediate signal intensity of the liver lesion
Unenhanced abdominal CT
Heterogeneous isodense mass at the segment VI of the liver.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Post-contrast arterial phase abdominal CT
Mild heterogeneous enhancement of the liver mass. Central parts of the mass do not enhance.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Post-contrast portal venous phase abdominal CT
Moderate enhancement is still seen except for central hypoattenuating areas.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Post-contrast equilibrium phase abdominal CT
There is persistent enhancement of the mass in this delayed phase.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
In-phase T1-weighted abdominal MR
Isointensity of the mass to the rest of the liver. The central part is hypointense.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Out-of-phase T1-weighted abdominal MR
There is no signal loss from the in-phase to the out-of-phase sequence.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Fat saturated T2-weighted abdominal MR
Hyperintensity of the periphery of the mass.
The central part is hypointense.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Arterial phase T1-weighted abdominal MR (Gd-EOB-DTPA)
Intense enhancement of the liver mass. The central part does not enhance.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Portal venous phase T1-weighted abdominal MR (Gd-EOB-DTPA)
There is still enhancement of the peripheral parts of the lesion.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Equilibrium phase T1-weighted abdominal MR (Gd-EOB-DTPA)
Washout of the lesion is seen at this phase.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Hepatocellular phase T1-weighted abdominal MR (Gd-EOB-DTPA)
Hypointensity of the lesion is well appreciated in this phase.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Diffusion weighted imaging (b=700)
The mass shows restricted diffusion
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Apparent diffusion coefficient map
Intermediate signal intensity of the liver lesion
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal