Abstract Introduction A hepatic angiomyolipoma is a rare benign tumor of the liver composed of a mixture of smooth muscle cells, blood vessels and a variable amount of adipose tissue. Differentiating them from malignant liver tumors can often be very difficult. Case presentation We report the case of a 43-year-old Caucasian man presenting with a large liver mass in the right lobe. The results of magnetic resonance imaging and contrast-enhanced ultrasonography were consistent with a well-demarcated adipose tissue- containing tumor, showing prolonged hyperperfusion in comparison with the surrounding liver tissue. Surgery was performed and the diagnosis of hepatic angiomyolipoma was made with histopathology. Conclusion Preoperative radiological characterization using magnetic resonance imaging and contrast-enhanced ultrasonography may improve diagnostic accuracy of hepatic angiomyolipoma. Identification of smooth muscle cells, blood vessels and adipose tissue with a positive immunohistochemical reaction for HMB-45 is the final evidence for an angiomyolipoma.</p

A Petrolla

Christian Lersch

CY Yang

GH Ding

Irene Esposito

Jochen Gaa

KG Ishak

N Ren

Oliver Ebert

P Flemming

R Li

Roland M. Schmid

Stephanie Krebs

ZG Chang

English

PubMed

Abstract Introduction A hepatic angiomyolipoma is a rare benign tumor of the liver composed of a mixture of smooth muscle cells, blood vessels and a variable amount of adipose tissue. Differentiating them from malignant liver tumors can often be very difficult. Case presentation We report the case of a 43-year-old Caucasian man presenting with a large liver mass in the right lobe. The results of magnetic resonance imaging and contrast-enhanced ultrasonography were consistent with a well-demarcated adipose tissue- containing tumor, showing prolonged hyperperfusion in comparison with the surrounding liver tissue. Surgery was performed and the diagnosis of hepatic angiomyolipoma was made with histopathology. Conclusion Preoperative radiological characterization using magnetic resonance imaging and contrast-enhanced ultrasonography may improve diagnostic accuracy of hepatic angiomyolipoma. Identification of smooth muscle cells, blood vessels and adipose tissue with a positive immunohistochemical reaction for HMB-45 is the final evidence for an angiomyolipoma.</p

Schmid Roland M

Gaa Jochen

Lersch Christian

Esposito Irene

Krebs Stephanie

Ebert Oliver

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Journal of Medical Case Reports

Preoperative radiological characterization of hepatic angiomyolipoma using magnetic resonance imaging and contrast-enhanced ultrasonography: a case report

Abstract
 
 Introduction
 A hepatic angiomyolipoma is a rare benign tumor of the liver composed of a mixture of smooth muscle cells, blood vessels and a variable amount of adipose tissue. Differentiating them from malignant liver tumors can often be very difficult.
 
 
 Case presentation
 We report the case of a 43-year-old Caucasian man presenting with a large liver mass in the right lobe. The results of magnetic resonance imaging and contrast-enhanced ultrasonography were consistent with a well-demarcated adipose tissue- containing tumor, showing prolonged hyperperfusion in comparison with the surrounding liver tissue. Surgery was performed and the diagnosis of hepatic angiomyolipoma was made with histopathology.
 
 
 Conclusion
 Preoperative radiological characterization using magnetic resonance imaging and contrast-enhanced ultrasonography may improve diagnostic accuracy of hepatic angiomyolipoma. Identification of smooth muscle cells, blood vessels and adipose tissue with a positive immunohistochemical reaction for HMB-45 is the final evidence for an angiomyolipoma.
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CASE REPORT Open Access
Preoperative radiological characterization of
hepatic angiomyolipoma using magnetic
resonance imaging and contrast-enhanced
ultrasonography: a case report
Stephanie Krebs1, Irene Esposito2, Christian Lersch1, Jochen Gaa3, Roland M Schmid1 and Oliver Ebert1*
Abstract
Introduction: A hepatic angiomyolipoma is a rare benign tumor of the liver composed of a mixture of smooth
muscle cells, blood vessels and a variable amount of adipose tissue. Differentiating them from malignant liver
tumors can often be very difficult.
Case presentation: We report the case of a 43-year-old Caucasian man presenting with a large liver mass in the
right lobe. The results of magnetic resonance imaging and contrast-enhanced ultrasonography were consistent
with a well-demarcated adipose tissue- containing tumor, showing prolonged hyperperfusion in comparison with
the surrounding liver tissue. Surgery was performed and the diagnosis of hepatic angiomyolipoma was made with
histopathology.
Conclusion: Preoperative radiological characterization using magnetic resonance imaging and contrast-enhanced
ultrasonography may improve diagnostic accuracy of hepatic angiomyolipoma. Identification of smooth muscle
cells, blood vessels and adipose tissue with a positive immunohistochemical reaction for HMB-45 is the final
evidence for an angiomyolipoma.
Introduction
An angiomyolipoma is a rare benign mesenchymal
tumor composed of a mixture of smooth muscle cells,
blood vessels and a variable amount of fat. The appear-
ance of an angiomyolipoma has often been reported in
the kidney but rarely in the liver. The first hepatic
angiomyolipoma was described by Ishak in 1976 [1]. It
can be found in both men and women, most commonly
in adult women. The majority of patients with hepatic
angiomyolipoma are asymptomatic. Others suffer from
abdominal pain and mild fever [2]. There is no histolo-
gical difference between an angiomyolipoma of the liver
or the kidney. A differentiation of malignant liver
tumors is often very difficult because of the high varia-
bility of the fat proportion.
Case presentation
A 43-year-old Caucasian man was found to have a large
echogenic mass in his right liver lobe by abdominal ultra-
sonography. The hepatic lesion measured about 5 × 9 cm
with a well-demarcated border (Figure 1A). Color Doppler
imaging showed intense vascularization in the periphery of
the tumor (Figure 1B). Five months prior to admission,
our patient had noticed chronic fatigue, a loss of efficiency
and abdominal stress under his right costal arch. A physi-
cal examination was unremarkable. Serum biochemistry
tests were without any pathological findings. The serologic
assay for viral hepatitis B and C were negative. The serum
alpha-fetoprotein level was 1.5 ng/mL (normal range < 6
ng/mL). Magnetic resonance imaging (MRI; 1.5T Magne-
tom Avanto, Siemens Medical Solutions, Erlangen, Ger-
many) of the liver mass using a native fat-suppressed T1-
weighted gradient echo sequence showed a fat-equivalent
signal behavior comparable to that of the subcutaneous
adipose tissue (Figure 1C). A contrast-enhanced ultrasono-
graphy (CEUS; Acuson Sequoia, Siemens Medical
* Correspondence: oliver.ebert@lrz.tum.de
1Medical Clinic, Klinikum rechts der Isar, Technische Universität München,
Munich, Germany
Full list of author information is available at the end of the article
Krebs et al. Journal of Medical Case Reports 2011, 5:481
http://www.jmedicalcasereports.com/content/5/1/481 JOURNAL OF MEDICAL
CASE REPORTS
© 2011 Krebs et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.
Solutions) was performed for further information. It
revealed a well-demarcated hyperechoic liver mass in seg-
ment VI, measuring 9.7 × 9.2 × 5.4 cm in maximum dia-
meter with a hypoechogenic portion. The margin was well
defined and smooth. The contrast agent (SonoVue, Bracco
International, Amsterdam, Netherlands) showed a hyper-
perfusion from the early to the late vascular phase in com-
parison with the surrounding liver tissue. There was no
sign of “halo” or “nodule-in-nodule” formation (Figure
1D).
After presenting all imaging results in an interdisciplin-
ary liver conference, an atypical resection of the right lobe
of his liver was recommended. Our patient underwent sur-
gery without any problems. After nine days, he left the
hospital in good clinical condition. The macroscopic
examination revealed a solitary tumor with a mottled yel-
low color and a soft consistency in the right lobe of his
liver (Figure 1E). The microscopic examination showed
that the tumor was well circumscribed but non-encapsu-
lated and consisted mostly of adipose tissue with solid
areas of elongated and rounded epithelioid cells, often
arranged around thick-walled blood vessels (Figure 1F and
1G). In the solid areas, the cells expressed smooth muscle
actin and the melanoma marker HMB-45 (Figure 1H).
Extramedullary hematopoiesis was not observed. A diag-
nosis of hepatic angiomyolipoma was made. Six months
after surgery our patient is in good clinical condition.
Chronic fatigue and loss of efficiency have disappeared.
Abdominal ultrasonography and serum biochemistry tests
were without any pathological findings.
Discussion
Hepatic angiomyolipoma has been considered as a
benign disease in the past. However, spontaneous tumor
rupture, malignant transformation and recurrence after
primary resection, as well as concurrent hepatic angio-
myolipoma and hepatocellular carcinoma, have been
reported [3,4]. Surgical resection should be considered
for all symptomatic patients. Conservative management
with close follow-up is suggested in patients with
asymptomatic tumors, good compliance and absence of
hepatitis virus infection, as well as small hepatic angio-
myolipoma (< 5 cm) that are diagnosed through fine-
needle aspiration biopsy [5].
Because of the variable amount of adipose tissue in
hepatic angiomyolipoma, it is sometimes difficult to dis-
tinguish between benign and malignant tumors. It is
possible to misdiagnose hepatic angiomyolipoma as
lipoma, hepatocellular adenoma or carcinoma, sarcoma
or metastasis before surgery. Contrast-enhanced spiral
computed tomography shows a marked enhancement in
the arterial and the portal venous phase of the soft tis-
sue components [5]. Recently, CEUS has been shown to
demonstrate typical imaging characteristics of hepatic
angiomyolipoma; an inhomogeneous hyperenhancing
pattern in arterial phase, prolonged hyperenhancing dur-
ing portal and late phase, with a smooth and well-
defined margin [6]. MRI is considered the best imaging
method to identify an angiomyolipoma. It shows a
hyperintensity on T2-weighted images and a hypointen-
sity on T1-weighted images, according to the amount of
adipose tissue [5].
Conclusion
Although the combination of various imaging modalities
increases preoperative diagnostic accuracy it is reported
to be less than 25% [7]. A definitive diagnosis is only
given by a histological examination after surgery.
Figure 1 Radiological and histopathological characterization of hepatic angiomyolipoma. (A) Detection of a hepatic lesion by abdominal
ultrasonography. (B) Color Doppler examination showing peripheral hypervascularization. (C) Typical MRI aspects of hepatic angiomyolipoma. (D)
CEUS findings. (E) Gross pathological findings after surgery. (F) Histological demonstration of mostly adipose tissue. (G) Demonstration of
epithelioid cells typically arranged around blood vessels. (H) Positive immunohistochemistry for the melanoma marker HMB-45.
Krebs et al. Journal of Medical Case Reports 2011, 5:481
http://www.jmedicalcasereports.com/content/5/1/481
Page 2 of 3
Identification of smooth muscle cells, blood vessels and
adipose tissue with a positive immunohistochemical
reaction for HMB-45 is the final evidence for an angio-
myolipoma [8].
Consent
Written informed consent was obtained from the patient
for publication of this case report and any accompany-
ing images. A copy of the written consent is available
for review by the Editor-in-Chief of this journal.
Author details
1Medical Clinic, Klinikum rechts der Isar, Technische Universität München,
Munich, Germany. 2Department of Pathology, Klinikum rechts der Isar,
Technische Universität München, Munich, Germany. 3Department of
Radiology, Klinikum rechts der Isar, Technische Universität München, Munich,
Germany.
Authors’ contributions
SK and OE wrote the manuscript. CL was the physician who performed
CEUS. JG was the radiologist in charge of the MRI. RMS gave final approval.
All authors read and approved the final manuscript.
Competing interests
The authors declare that they have no competing interests.
Received: 20 May 2011 Accepted: 26 September 2011
Published: 26 September 2011
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doi:10.1186/1752-1947-5-481
Cite this article as: Krebs et al.: Preoperative radiological
characterization of hepatic angiomyolipoma using magnetic resonance
imaging and contrast-enhanced ultrasonography: a case report. Journal
of Medical Case Reports 2011 5:481.
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Krebs et al. Journal of Medical Case Reports 2011, 5:481
http://www.jmedicalcasereports.com/content/5/1/481
Page 3 of 3

Common and epithelioid variant of hepatic angiomyolipoma exhibit clonal growth and share a distinctive immunophenotype. Hepatology

Cong WM: Diagnosis and treatment of hepatic angiomyolipoma.

Diagnosis and treatment of hepatic angiomyolipoma in 26 cases.

Mesenchymal tumors of the liver. In Hepatocellular carcinoma. Edited by: Okuda K, Peters RL.

PH: Management of hepatic angiomyolipoma.

X: Real-time contrast-enhanced ultrasonography of resected and immunohistochemically proven hepatic angiomyolipomas. Abdominal Imaging

Xin W: Hepatic angiomylipoma. Arch Pathol Lab Med

YP: Characteristics and treatment strategy of hepatic angiomyolipoma: a series of 94 patients collected from four institutions. J Gastrointestin Liver Dis

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=3189154

Preoperative radiological characterization of hepatic angiomyolipoma using magnetic resonance imaging and contrast-enhanced ultrasonography: a case report

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