DOI:10.2214/AJR.05.0659
AJR 2006; 187:W481-W489
© American Roentgen Ray Society
Unusual Mesenchymal Liver Tumors in Adults: Radiologic-Pathologic Correlation
Kyoung Ah Kim1,
Kyoung Won Kim1,
Seong Ho Park1,
Se Jin Jang2,
Mi-Suk Park3,
Pyo Nyun Kim1,
Moon-Gyu Lee1 and
Hyun Kwon Ha1
1 Department of Radiology, University of Ulsan College of Medicine and Asan
Medical Center, 388-1, Pungnap-2 dong, Songpa-ku, Seoul 138-736, South
Korea.
2 Department of Diagnostic Pathology, University of Ulsan College of Medicine
and Asan Medical Center, Seoul, South Korea.
3 Department of Radiology, YounDong Severance Hospital, Seoul, South
Korea.
Received April 16, 2005;
accepted after revision July 22, 2005.
Address correspondence to K. W. Kim
(kimkw{at}amc.seoul.kr).
WEB
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Abstract
OBJECTIVE. Our purpose was to review a broad spectrum of mesenchymal
liver tumors in adults and present their cross-sectional imaging
characteristics including radiologic-pathologic correlation.
CONCLUSION. Cross-sectional imaging findings of mesenchymal liver
tumors in adults are varied and some may overlap with others or even with more
common malignant epithelial tumors. However, in some cases, their appearances
at cross-sectional imaging studies may reflect characteristic abnormalities
that suggest a specific diagnosis. Therefore, familiarity with the radiologic
findings of mesenchymal liver tumors and understanding their pathological
background is important for increasing the accuracy of radiologic
diagnosis.
Keywords: hepatobiliary imaging • liver disease • oncologic imaging • radiologic-pathologic correlation
Introduction
Primary hepatic tumors can arise from different components of the liver
such as hepatocytes, bile duct epithelia, neuroendocrine cells, and
mesenchymal cells. Among those, primary mesenchymal tumors of the liver are
defined as benign and malignant tumors with vascular, fibrous, adipose, and
other mesenchymal tissue differentiation. These tumors may have variable
appearances on radiology and present a diagnostic challenge. Although some
mesenchymal tumors may exhibit overlapping radiologic findings that make
differentiation difficult, others may have characteristic appearances on
cross-sectional imaging that reflect pathologic features. However, except for
cavernous hemangioma, which is the most common benign tumor of the liver,
mesenchymal liver tumors are rarely encountered in adults and, to our
knowledge, there has been a lack of comprehensive review of these lesions. In
this article, we review a broad spectrum of mesenchymal liver tumors in adults
and present their cross-sectional imaging characteristics with
radiologic-pathologic correlation.
Mesenchymal Hamartoma
Mesenchymal hamartoma of the liver is a rare mesenchymal lesion, with both
a cystic and a solid compartment, composed of an admixture of bile ducts,
hepatocytes, and mesenchymal tissue. It is thought to be a developmental
anomaly rather than a true neoplasm. Mesenchymal hamartoma has a predilection
for infants and usually manifests between the ages of 4 months and 2 years; it
rarely occurs in adults. Mesenchymal hamartoma in adults may show a series of
histologic modifications—that is, progressive loss of hepatocytes,
degeneration of bile duct epithelium, and cystic changes of the mesenchymal
component. The margin between the liver and the lesion is distinct, but a true
capsule is generally not present. On the cut surface are multiple cysts in an
edematous stroma; the cysts vary in size, from millimeters to 15 cm, and in
number and distribution, being discrete or connected. Their appearances on
cross-sectional imaging may reflect these spectra of cystic changes observed
pathologically and can range from multiple small cysts in a solid mass
resembling Swiss cheese to a multilocular cystic mass with intervening solid
septa. The solid component may show a varying degree of enhancement after
contrast administration [1]
(Figs. 1A,
1B,
1C,
1D, and
1E). Biliary cystadenocarcinoma
and hepatocellular carcinoma with cystic degeneration may also present as an
admixture of a solid and cystic mass and may be included in the differential
diagnoses.
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Fig. 1A —40-year-old woman with mesenchymal hamartoma in right hepatic
lobe that was incidentally found at sonography. Transverse sonogram shows
large mass composed of admixture of cystic (arrowheads) and solid
(arrows) compartments in right lobe of liver.
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Fig. 1B —40-year-old woman with mesenchymal hamartoma in right hepatic
lobe that was incidentally found at sonography. Color Doppler sonogram shows
hypervascularity in solid portion (arrowheads) of mass.
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Fig. 1C —40-year-old woman with mesenchymal hamartoma in right hepatic
lobe that was incidentally found at sonography. Contrast-enhanced CT scan
shows strong enhancement in solid portion (arrow) and mild
enhancement in intervening septa (arrowheads) between cystic
parts.
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Fig. 1D —40-year-old woman with mesenchymal hamartoma in right hepatic
lobe that was incidentally found at sonography. On coronal true fast image
with steady-state free precession (FISP), solid component and intervening
septa are seen as intermediate high signal intensity, whereas cystic portion
is seen as bright high signal intensity.
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Fig. 1E —40-year-old woman with mesenchymal hamartoma in right hepatic
lobe that was incidentally found at sonography. Low-power photomicrograph
shows thick-walled vessels and bile ducts embedded in dense fibrous stroma,
suggestive of mesenchymal hamartoma. (H and E, original magnification
x20)
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Angiomyolipoma
Angiomyolipoma is a benign tumor composed of variable admixtures of adipose
tissue, smooth muscle, and thick-walled blood vessels, with occasional foci of
extramedullary hemopoiesis. The fat component of hepatic angiomyolipoma varies
between 10% and 90%. Hepatic angiomyolipoma usually presents as a single
sharply demarcated but not encapsulated mass in an asymptomatic adult without
sex difference. A small number of cases are associated with tuberous
sclerosis. Although most of these tumors are found incidentally on routine
sonographic or crosssectional imaging, the accuracy of radiologic diagnosis
may be low because variable proportions of fatty tissue in the tumors may
result in various appearances and because of the rarity of the lesion.
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Fig. 2A —43-year-old woman with angiomyolipoma in right hepatic lobe
that was incidentally found at sonography. Oblique sagittal sonogram shows
ovoid echogenic mass (arrows) in right lobe of liver.
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Fig. 2B —43-year-old woman with angiomyolipoma in right hepatic lobe
that was incidentally found at sonography. Unenhanced CT scan shows
hypoattenuation of lesion (arrows) compared with liver parenchyma,
but attenuation is not as low as that of subcutaneous fat.
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Fig. 2C —43-year-old woman with angiomyolipoma in right hepatic lobe
that was incidentally found at sonography. Contrast-enhanced CT scan during
hepatic artery phase shows hypervascular staining of tumor
(arrows).
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Fig. 2D —43-year-old woman with angiomyolipoma in right hepatic lobe
that was incidentally found at sonography. On contrast-enhanced CT scan during
portal venous phase, lesion is seen as hypoattenuation (arrows).
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Fig. 2E —43-year-old woman with angiomyolipoma in right hepatic lobe
that was incidentally found at sonography. High-power photomicrograph shows
admixture of adipose tissue, smooth muscle, and thick-walled blood vessels,
suggesting diagnosis of angiomyolipoma. (H and E, original magnification
x200)
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Fig. 2F —43-year-old woman with angiomyolipoma in right hepatic lobe
that was incidentally found at sonography. On immunohistochemical study,
specimen shows positivity for human melanocyte-specific antibody (HMB 45),
supporting diagnosis of angiomyolipoma.
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The tumor may be seen as an echogenic mass, either homogeneous or
heterogeneous, on sonography. CT may confirm the presence of fat when the
attenuation value is less than -20 H, but not infrequently the lesions may
exhibit heterogeneous CT density (Figs.
2A,
2B,
2C,
2D,
2E, and
2F). Using fat-suppression
sequences or chemical shift imaging, MRI may facilitate the diagnosis. In
addition to angiomyolipoma, the differential diagnoses of heterogeneous
fat-containing liver lesions may also include angiolipoma, adenoma, and
metastatic neoplasms, such as hepatocellular carcinoma, malignant teratoma,
and liposarcoma [2].
Myofibroblastoma
Myofibroblastoma or inflammatory pseudotumor, defined as a localized mass
consisting of a fibrous stroma, proliferated myofibroblasts, chronic
inflammatory infiltration with plasma cells, and the absence of anaplasia,
rarely occurs in the liver and has a predilection for young males (male:female
ratio is 8:1). The cause of this entity remains unclear, although infection
and biliary obstruction have been suggested as causes. This lesion is usually
solitary (81%) and less often multiple (19%) and is usually intrahepatic, but
some can involve the hepatic hilum. Unlike its pulmonary counterpart, hepatic
inflammatory pseudotumor tends to cause one or more systemic symptoms,
including fever, epigastric pain, vomiting, general malaise, and weight
loss.
Radiologically, although a variable degree of contrast enhancement may be
seen on CT during the portal venous phase, at least a part of the lesion may
show greater contrast enhancement on delayed phase CT than liver parenchyma,
presumably because of the abundant fibrous tissue in this lesion
[3,
4] (Figs.
3A,
3B,
3C,
3D, and
3E). However, because hepatic
metastasis and peripheral cholangiocarcinoma may also have abundant fibrosis
and produce delayed contrast enhancement
[5], the differentiation from
these lesions on the basis of CT findings alone may be difficult. Although
this lesion may mimic malignant disease in its gross appearance and imaging
findings, clinical findings usually suggest an active inflammatory process;
this lesion has a benign histologic appearance and course
[3]. The differential diagnoses
may include chronic organizing abscess, metastasis, peripheral
cholangiocarcinoma, and hepatocellular carcinoma with sclerosis.
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Fig. 3A —34-year-old woman with myofibroblastoma in right hepatic lobe
that was incidentally found on sonography. Transverse sonogram shows
predominantly cystic mass with multiple internal septa (arrowheads)
and eccentrically located solid portion (arrows) in liver.
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Fig. 3B —34-year-old woman with myofibroblastoma in right hepatic lobe
that was incidentally found on sonography. T2-weighted axial MR image well
shows admixture of solid and cystic mass (arrowheads).
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Fig. 3C —34-year-old woman with myofibroblastoma in right hepatic lobe
that was incidentally found on sonography. Delayed phase contrast-enhanced MR
image after administration of gadopentetate dimeglumine shows intense
enhancement in solid portion (arrowheads). This finding correlates
with abundant fibrous tissue seen on histopathologic examination.
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Fig. 3D —34-year-old woman with myofibroblastoma in right hepatic lobe
that was incidentally found on sonography. Photograph of specimen shows
predominantly cystic mass with trabeculated internal surface.
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Fig. 3E —34-year-old woman with myofibroblastoma in right hepatic lobe
that was incidentally found on sonography. Low-power photomicrograph shows
abundant fibrous tissue and inflammatory cells consisting of plasma cells,
lymphocytes, neutrophils, and occasional eosinophils. (H and E, original
magnification x40)
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Epithelioid Hemangioendothelioma
Epithelioid hemangioendothelioma is a rare hepatic tumor of low- to
intermediate-grade malignancy. Histologically, epithelioid or dendritic cells
growing along preformed vessels or forming new vessels characterize the
tumors, and the stroma is fibrous with myxohyaline areas. Although tumor
nodules grossly appear discrete, they are infiltrative microscopically. The
lesions are usually multifocal, and nodules may coalesce in the periphery of
the liver, forming large confluent masses, and may evolve to be associated
with progressive fibrosis and calcification. Neoplastic endothelial cells
invade and eventually obliterate sinusoids and the tributaries of the portal
and hepatic veins. This tendency for intravascular growth predisposes the
tumor to occlude its own blood supply, resulting in "suicide"
ischemia [6].
Imaging findings of epithelioid hemangioendothelioma have been well
documented. Sonographically, it may be seen as multiple discrete nodules, or
the liver may have a diffusely heterogeneous echotexture in regions of
extensive involvement. The individual lesions may show variable echogenicity
and, most frequently, they are hypoechoic relative to liver parenchyma. On CT,
epithelioid hemangioendothelioma is usually seen as multiple discrete nodules
with a target appearance or as a confluent hypodense mass in the liver
periphery extending to the capsular margin (Figs.
4A,
4B,
4C,
4D,
4E, and
4F). Capsular retraction
adjacent to the mass is seen less than 25% of cases.
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Fig. 4A —32-year-old woman with epithelioid hemangioendotheliomas in
hepatic right lobe who presented with epigastric pain for 2 months. Oblique
sagittal sonogram shows multiple ill-defined hypoechoic lesions with target
appearance (arrowheads) in right lobe of liver.
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Fig. 4B —32-year-old woman with epithelioid hemangioendotheliomas in
hepatic right lobe who presented with epigastric pain for 2 months.
Contrast-enhanced CT scan shows multiple discrete low-attenuation lesions
(arrows) in periphery of right hepatic lobe. Capsular retraction
(arrowheads) adjacent to one nodule and extending to capsular surface
is clearly seen.
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Fig. 4C —32-year-old woman with epithelioid hemangioendotheliomas in
hepatic right lobe who presented with epigastric pain for 2 months.
T2-weighted axial MR image shows heterogeneous high signal intensity of
lesions with target appearance (arrows) and capsular retraction
(arrowheads).
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Fig. 4D —32-year-old woman with epithelioid hemangioendotheliomas in
hepatic right lobe who presented with epigastric pain for 2 months.
T2-weighted axial MR image shows another target appearance of lesion with
central areas of low signal intensity (arrowhead).
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Fig. 4E —32-year-old woman with epithelioid hemangioendotheliomas in
hepatic right lobe who presented with epigastric pain for 2 months. High-power
photomicrograph shows spindle or oval tumor cells scattered in fibromyxoid
stroma. Some tumor cells show intracytoplasmic vacuoles. (H and E, original
magnification x200)
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Fig. 4F —32-year-old woman with epithelioid hemangioendotheliomas in
hepatic right lobe who presented with epigastric pain for 2 months. On
immunohistochemical staining, tumor cells show positivity for CD34
antigen.
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MRI usually shows low signal intensity of the lesions relative to liver
parenchyma on T1-weighted sequences and heterogeneous high signal intensity on
T2-weighted sequences. Some lesions may have a target appearance on
T2-weighted images. In those cases, central areas of low signal intensity may
correspond to areas of hemorrhage, coagulation necrosis, and calcification;
and peripheral high signal intensity corresponds to edematous connective
tissue and viable tumor. After the IV administration of gadopentetate
dimeglumine, peripheral enhancement and a thin nonenhancing rim corresponding
to a narrow avascular zone between normal liver and nodule may be seen
[7].
The multinodular form of endothelial hemangioendothelioma is
indistinguishable from metastatic disease. Its temporal evolution into the
diffuse form with its peripheral subcapsular growth, increased vascularity,
and associated hypertrophy of the uninvolved liver may favor the diagnosis of
endothelial hemangioendothelioma
[6].
Angiosarcoma
Hepatic angiosarcoma is a malignant mesenchymal tumor composed of spindle
or pleomorphic cells that are vasoformative, forming poorly organized vessels,
or line or grow into the preformed vascular spaces such as sinusoids and small
veins [6]. Although a rare
malignancy, hepatic angiosarcoma is nevertheless the most common sarcoma of
the liver; it is four times more common in men than in women. Hepatic
angiosarcoma is the quintessential example of malignant transformation
secondary to environmental exposure to chemical carcinogens such as Thorotrast
(thorium oxide, a previously used contrast agent), vinyl chloride monomer,
arsenic, and androgenic anabolic steroids. However, exposure to these agents
is now rare, and these tumors more commonly occur in the absence of known risk
factors [8].
Patients with hepatic angiosarcomas have a poor prognosis; most have
metastatic lesions at the time of presentation, most commonly in the lung and
spleen, and these patients die within a year of diagnosis. The gross
appearance of hepatic angiosarcoma at pathologic examination is characterized
by the presence of remarkable necrosis and hemorrhage. Angiosarcomas may be
classified into four types according to their growth pattern: multiple
nodules; a large solitary mass; a mixed pattern of a dominant mass with
nodules; and rarely, a diffuse infiltrating micronodular tumor. Fibrosis and
deposition of hemosiderin are frequently seen in solid portions of the
tumor.
Radiologically, hepatic angiosarcomas may exhibit a spectrum of appearances
that reflect its various pathologic features. Major differential diagnoses
include metastases, hemangioma, and hepatocellular carcinoma. Hepatic
angiosarcomas may be seen as either single or multiple masses that are
predominantly hypoattenuating compared with surrounding hepatic parenchyma on
unenhanced CT, but they may be mixed with an area of hyperattenuation caused
by fresh internal hemorrhage or with areas of low attenuation near that of
fluid, representing the site of old hemorrhage
[6]. On contrast-enhanced CT,
when the tumors appear as multiple nodular lesions, most lesions are
hypoattenuating and foci of enhancement may be present. Such enhancement may
be less than that of the aorta and is often bizarre in shape, with ring
enhancement seen in some nodules so that they are clearly distinguishable from
the nodular enhancement in benign hemangiomas. When the tumor appears as a
dominant mass, dynamic contrast-enhanced CT may show heterogeneous and
progressive enhancement [8]
(Figs. 5A,
5B,
5C, and
5D). On MRI, the signal
intensity characteristics of hepatic angiosarcoma may parallel those of
hemangioma [6], but sometimes a
heterogeneous internal architecture similar to that of hepatocellular
carcinoma may be shown [8].
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Fig. 5A —24-year-old man with angiosarcomas in both hepatic lobes who
presented with epigastric pain for 2 months. Unenhanced CT scan shows multiple
masses that are predominantly hypoattenuating compared with surrounding
hepatic parenchyma mixed with hyperattenuation area (arrow) caused by
fresh internal hemorrhage. Note also areas of low attenuation near that of
fluid (arrowheads), representing site of old hemorrhage.
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Fig. 5B —24-year-old man with angiosarcomas in both hepatic lobes who
presented with epigastric pain for 2 months. On contrast-enhanced CT scan
during hepatic artery phase, most lesions are seen as hypoattenuating, and
foci of enhancement are present. Such enhancement is bizarre in shape, with
ring enhancement seen in some nodules (arrowheads).
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Fig. 5C —24-year-old man with angiosarcomas in both hepatic lobes who
presented with epigastric pain for 2 months. Low-power photomicrograph shows
that tumor nodule is composed of pleomorphic endothelial cells, fibrous septa
with atypical endothelial cells, and blood pooling. (H and E, original
magnification x40)
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Fig. 5D —24-year-old man with angiosarcomas in both hepatic lobes who
presented with epigastric pain for 2 months. On immunohistochemical staining,
tumor cells show positivity for coagulation factor VIII.
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Undifferentiated Embryonal Sarcoma
Undifferentiated embryonal sarcoma is an unusual malignant mesenchymal
liver tumor that occurs predominantly in older children and adolescents (mean
age, 12 years), but this tumor also is rarely encountered in adults. The
histopathologic pattern of this tumor is that of a rapidly growing,
undifferentiated tumor with frequent mitosis. Gross appearance of the tumor
can range from predominantly solid to cystic lesions, and the cut surface may
have cystic areas of variable size that contain necrotic debris, hemorrhagic
fluid, clotted blood, and gelatinous material.
Sonographically, undifferentiated embryonal sarcoma may be seen as a large,
well-defined mixed echogenic mass with multiple small anechoic spaces
reflecting pathologic features. However, this tumor may have a misleading
cystlike appearance on CT and MRI compared with sonographic and pathologic
findings. In other words, in most of the tumor volume, CT may show low
attenuation (approximately that of water) and T2-weighted MR images show high
signal intensity (approximately equal to that of cerebrospinal fluid)
[9] (Figs.
6A,
6B,
6C, and
6D). Therefore, sonography may
be helpful to differentiate this tumor from predominantly cystlike masses on
CT and MRI, such as biliary cystadenoma and cystadenocarcinoma, cystic
degeneration of hepatocellular carcinoma, cholangiocarcinoma, abscess,
metastatic disease, and posttraumatic resolving hematoma
[9].
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Fig. 6A —44-year-old woman with undifferentiated embryonal sarcoma in
left hepatic lobe who presented with right upper quadrant discomfort for 1
year. Transverse sonogram shows large, well-defined, mixed echogenic mass with
multiple anechoic spaces (asterisk) in left hepatic lobe.
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Fig. 6B —44-year-old woman with undifferentiated embryonal sarcoma in
left hepatic lobe who presented with right upper quadrant discomfort for 1
year. Unenhanced CT scan shows low-attenuation mass with well-demarcated
margin nearly replacing left lateral segment of liver.
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Fig. 6C —44-year-old woman with undifferentiated embryonal sarcoma in
left hepatic lobe who presented with right upper quadrant discomfort for 1
year. On contrast-enhanced CT scan, mass is seen as misleading cystlike
appearance, but mild septalike peripheral enhancement (arrowheads) is
also seen.
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Fig. 6D —44-year-old woman with undifferentiated embryonal sarcoma in
left hepatic lobe who presented with right upper quadrant discomfort for 1
year. High-power photomicrograph shows malignant cells that are stellate or
spindle in shape and compactly arranged in a myxoid stroma with
pseudocapsule.
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Malignant Fibrous Histiocytoma
Malignant fibrous histiocytoma is a wellknown pathologic entity that
primarily involves the soft tissue of all organs. However, primary malignant
fibrous histiocytoma of the liver is rare. Most reported cases have occurred
in adults over 50 years old with no predilection for either sex. The
microscopic features of primary malignant fibrous histiocytoma of the liver
are similar to those of its soft-tissue counterpart: a pleomorphic-storiform
pattern, giant cells, and foci of necrosis. The other histologic variants,
such as inflammatory and angiomatoid types, have not been reported in primary
liver lesions.
Radiology reports of primary malignant fibrous histiocytoma of the liver
are limited and show the general features of malignant tumors. However, a
complex internal architecture of this tumor, with abundant fibrosis, myxoid
degeneration, and hemorrhagic necrosis, may be reflected on radiologic
studies. The tumor may be seen as a hypodense lesion with profound
low-attenuation areas of necrosis on unenhanced CT. Dynamic contrast-enhanced
CT may show gradual, inhomogeneous, and multiple irregular septalike streaky
areas of enhancement, and the extent and pattern of contrast enhancement on
delayed phase scanning may be variable, depending on the amount of fibrosis
[10] (Figs.
7A,
7B, and
7C). However, radiologically,
there may be considerable overlap between this tumor and other hypovascular
malignant hepatic tumors or even hepatic abscesses, and their differentiation
may be difficult.
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Fig. 7A —44-year-old man with malignant fibrous histiocytoma in right
hepatic lobe who presented with right upper quadrant discomfort for 6 months.
Unenhanced CT scan shows large hypodense mass with profound low-attenuation
areas of necrosis (asterisk).
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Fig. 7B —44-year-old man with malignant fibrous histiocytoma in right
hepatic lobe who presented with right upper quadrant discomfort for 6 months.
Contrast-enhanced CT scan during portal venous phase shows inhomogeneous and
multiple irregular septalike streaky areas of enhancement in periphery.
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Fig. 7C —44-year-old man with malignant fibrous histiocytoma in right
hepatic lobe who presented with right upper quadrant discomfort for 6 months.
Photograph of cut surface of gross specimen shows mass composed of ill-defined
white, whirled, and fibrous tissue, with multifocal necrotic and focal
hemorrhagic lesions. Hepatic capsule is not involved.
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Other Hepatic Sarcomas
Other primary hepatic sarcomas such as rhabdomyosarcoma, leiomyosarcoma,
localized malignant mesothelioma, and Kaposi sarcoma are extremely rare and
have been the subject of case reports. Among these tumors, malignant
mesothelioma occasionally occurs from the inner layer of Glisson's capsule or
from the fibrous connective tissues and may grow into the liver parenchyma or
can be pedunculated. Because of the rarity of malignant mesotheliomas and
because the radiologic features of this tumor are nonspecific, it is rarely
diagnosed preoperatively. Malignant mesothelioma may be seen as a large mass
that contains multiple cystic spaces with thick septations and hemorrhage, and
the patient may have history of occupational asbestos exposure
[11].
Conclusion
Cross-sectional imaging findings of mesenchymal liver tumors in adults are
varied, and overlapping may occur between them, especially with the more
common malignant epithelial tumors. Although a definitive diagnosis in most of
these cases should be confirmed by histopathology, sometimes appearances at
cross-sectional imaging may reflect characteristic pathologic features.
Therefore, familiarity with the radiologic findings of mesenchymal liver
tumors and an understanding of their pathologic background are important both
for narrowing the list of differential diagnoses and for increasing the chance
of an accurate radiologic diagnosis.
References
- Horton KM, Bluemke DA, Hruban RH, Soyer P, Fishman EK. CT and MR
imaging of benign hepatic and biliary tumors.
RadioGraphics 1999;19
: 431-451[Abstract/Free Full Text]
- Ahmadi T, Itai Y, Takahashi M, et al. Angiomyolipoma of the liver:
significance of CT and MR dynamic study. Abdom Imaging1998; 23:520
-526[CrossRef][Medline]
- Fukuya T, Honda H, Matsumata T, et al. Diagnosis of inflammatory
pseudotumor of the liver: value of CT. AJR1994; 163:1087
-1091[Abstract/Free Full Text]
- Yoshikawa J, Matsui O, Kadoya M, Gabata T, Arai K, Takashima T.
Delayed enhancement of fibrotic areas in hepatic masses: CT-pathologic
correlation. J Comput Assist Tomogr 1992;16
: 206-211[Medline]
- Burgener FA, Hamlin DJ. Contrast enhancement of focal hepatic
lesions in CT: effect of size and histology. AJR1983; 140:297
-301[Abstract/Free Full Text]
- Buetow PC, Buck JL, Ros PR, Goodman ZD. Malignant vascular tumors
of the liver: radiologic-pathologic correlation.
RadioGraphics 1994;14
: 153-166[Abstract]
- Lyburn ID, Torreggiani WC, Harris AC, et al. Hepatic epithelioid
hemangioendothelioma: sonographic, CT, and MR imaging appearances.
AJR 2003; 180:1359
-1364[Free Full Text]
- Koyama T, Fletcher JG, Johnson CD, Kuo MS, Notohara K, Burgart LJ.
Primary hepatic angiosarcoma: findings at CT and MR imaging.
Radiology 2002;222
: 667-673[Abstract/Free Full Text]
- Buetow PC, Buck JL, Pantongrag-Brown L, et al. Undifferentiated
(embryonal) sarcoma of the liver: pathologic basis of imaging findings in 28
cases. Radiology 1997;203
: 779-783[Abstract/Free Full Text]
- Yu JS, Kim KW, Kim CS, Yoon KH, Jeong HJ, Lee DG. Primary malignant
fibrous histiocytoma of the liver: imaging features of five surgically
confirmed cases. Abdom Imaging 1999;24
: 386-391[CrossRef][Medline]
- Leonardou P, Semelka RC, Kanematsu M, Braga L, Woosley JT. Primary
malignant mesotheliomas of the liver: MR imaging findings. Magn
Reson Imaging 2003; 21:1091
-1093[CrossRef][Medline]
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Abstract
Introduction
