DOI:10.2214/AJR.05.0544
AJR 2007; 189:W160-W162
© American Roentgen Ray Society
Three-Phase Dynamic CT of Pelioid Hepatocellular Carcinoma
Young Kon Kim1,
Kyu Yun Jang2,
Baik Hwan Cho3,
Seog Wan Ko1 and
Woo Sung Moon2
1 Department of Diagnostic Radiology, Chonbuk National University Medical School
and Hospital, Jeonju, Korea.
2 Department of Pathology, Chonbuk National University and Hospital, KeumAm-dong
634-18, Jeonju, Korea.
3 Department of General Surgery, Chonbuk National University Medical School and
Hospital, Jeonju, Korea.
Received April 7, 2005;
accepted after revision August 23, 2005.
Supported by the Korean Ministry of Science and Technology through the
Center for Healthcare Technology Development.
Address correspondence to W. S. Moon
(mws{at}chonbuk.ac.kr).
WEB
This is a Web exclusive article.
Keywords: CT • hepatocellular carcinoma • liver
Introduction
Hepatocellular carcinoma (HCC) is the most frequent primary malignant tumor
of the liver. Because radiologic investigations have elucidated the
hemodynamics of HCC, most typical cases of HCC can be accurately diagnosed on
the basis of characteristic enhancement patterns: early enhancement in the
arterial phase and washout during the portal and delayed phases of
contrast-enhanced dynamic imaging, including CT and MRI
[1]. Atypical radiologic
manifestations of HCC, however, have been commonly encountered, and most of
these tumors are of a hypovascular nature; that is, they exhibit low
attenuation during the arterial phase of dynamic imaging
[2]. Pelioid HCC is a rare
histologic type of HCC [3]. To
our knowledge, the radiologic findings on this tumor have not been reported in
the English-language radiology literature. We describe the three-phase dynamic
CT findings in a case of surgically confirmed huge pelioid HCC with two small
daughter nodules.
Case Report
A 69-year-old man was referred for evaluation of a huge liver mass that had
been detected with sonography. He reported abdominal pain and discomfort in
the right upper quadrant. The hepatitis B virus antigen result was positive,
but we found no evidence of liver cirrhosis at either histologic analysis of
the surgical specimen or on imaging. The patient had no other relevant medical
history. The blood test results showed mild hepatic dysfunction with mildly
elevated levels of serum aspartate aminotransferase and alanine
aminotransferase. The serum 
-fetoprotein level was in the normal
range.
CT was performed with a 16-MDCT scanner (Sensation 16, Siemens Medical
Solutions). After unenhanced images were obtained, dynamic three-phase imaging
was begun. The hepatic arterial, portal venous, and delayed phases were begun
35, 70, and 180 seconds, respectively, after the start of injection of
contrast medium. Dynamic CT revealed a huge (15 cm) mass in the right lobe of
the liver. The arterial dominant phase showed minimal, irregular bright
enhancement equal to the attenuation of the adjacent aorta in the periphery of
the huge mass. Irregular low attenuation was found in the central area of the
tumor (Fig. 1A). In addition,
two masses measuring approximately 2 cm in diameter appeared as homogeneous
areas of high attenuation in the inferior portion of the right hepatic lobe
inferolateral to the main mass. On portal venous phase imaging, the enhancing
area in the main mass increased except for a central area of irregular low
attenuation (Fig. 1B), and the
two daughter masses appeared as areas of isoattenuation adjacent to the liver.
On delayed phase imaging, the enhancing area appeared larger than in the two
earlier phases, mimicking centripetal enhancement
(Fig. 1C). Also in the delayed
phase, multifocal scattered areas of low attenuation relative to adjacent
liver were visualized in the enhancing portions of the main mass, and a
capsule-like rim of enhancement was found
(Fig. 1C). The two daughter
masses adjacent to the main mass appeared as areas of low attenuation on
delayed phase images. This finding is a typical imaging feature of a
hypervascular HCC.
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Fig. 1A —45-year-old man with three surgically proven pelioid
hepatocellular carcinomas, including one large main mass and two adjacent
daughter nodules. Arterial phase CT scan at lower level of liver shows large
main mass (large arrows) with minimal irregular peripheral bright
enhancement equal to attenuation of adjacent aorta. Two daughter nodules
(small arrows) adjacent to main mass appear as areas of homogeneous
high attenuation.
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Fig. 1B —45-year-old man with three surgically proven pelioid
hepatocellular carcinomas, including one large main mass and two adjacent
daughter nodules. Portal venous phase CT scan at level above A shows
progressive fill-in enhancement in periphery of main mass, except for central
necrotic area.
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Fig. 1C —45-year-old man with three surgically proven pelioid
hepatocellular carcinomas, including one large main mass and two adjacent
daughter nodules. Delayed phase (3 minutes) CT scan shows increased size of
enhancing area in periphery of main mass compared with two earlier phases.
Areas of slightly lower attenuation (large arrows) are evident in
enhancing portion of main mass. Capsule-like enhancement (small
arrows) also is evident. Two daughter nodules had low attenuation (not
shown).
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The huge main mass and the two adjacent daughter nodules were surgically
resected. The gross pathologic examination revealed an encapsulated
heterogeneous main mass consisting of an irregular area of central necrosis
and peripheral solid portions containing blood-filled cavities
(Fig. 1D). The two daughter
nodules (Fig. 1D) were soft and
yellowish. At gross examination, the main mass resembled a giant cavernous
hemangioma with hemorrhage, but a fibrous capsule, which is frequently found
in typical HCC, also was found (Fig.
1D). Microscopic examination of the main mass and the two daughter
nodules showed well-differentiated HCC cells that corresponded to grade I or
II HCC, according to Edmonson's
[4] classification. These cells
were intermingled with vascular channels, so the tumors were classified as
pelioid HCC (Figs. 1E and
1F). The blood cavities of the
tumors were different from those of typical cavernous hemangioma, which
generally has a single layer of endothelial cells lining the vascular
channels. Because the blood cavities of the tumor were surrounded by HCC cells
and because some of the cavities were devoid of an endothelial lining, the
lesion resembled peliosis hepatis. The relative proportion of pelioid spaces
to cancer cells in the main mass was remarkably higher than in the two
daughter nodules (Figs. 1E and
1F). Microvascular invasion of
tumor cells, another common feature of HCC, also was found.
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Fig. 1D —45-year-old man with three surgically proven pelioid
hepatocellular carcinomas, including one large main mass and two adjacent
daughter nodules. Photograph of gross specimen shows well-defined
heterogeneous main mass consisting of central irregular necrosis and
peripheral solid portions containing blood-filled cavities. Fibrotic capsule
(large arrows) is evident. Two daughter nodules (small
arrows) are adjacent to main mass.
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Fig. 1E —45-year-old man with three surgically proven pelioid
hepatocellular carcinomas, including one large main mass and two adjacent
daughter nodules. Photomicrograph of specimen from main mass shows cancer
cells of well-differentiated hepatocellular carcinoma (large arrows)
intermingled with pelioid space (small arrows). (H and E,
x40)
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Fig. 1F —45-year-old man with three surgically proven pelioid
hepatocellular carcinomas, including one large main mass and two adjacent
daughter nodules. Photomicrograph of specimen from daughter nodules shows
components of both well-differentiated hepatocellular carcinoma (large
arrows) and pelioid space (small arrows). However, relative
proportion of pelioid space to cancer cells was remarkably less than in main
mass. (H and E, x100)
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Discussion
HCC has been classified according to the predominant histologic pattern.
The most common subtype is trabecular (43% of cases) followed by pseudoacinar
(13%), compact small cell (10%), clear cell (8%), and undifferentiated (10%)
[3]. Although the features of
HCC on dynamic CT and MRI have been well described, histologic pattern has not
been correlated with imaging findings, except in the case of fibrolamellar HCC
[5]. Pelioid HCC is a rare
histologic type of HCC, and the radiologic findings have not been described,
except in one report on the 99Tc-RBC scintigraphic findings in a
patient with pelioid HCC
[6].
In our patient, two different three-phase dynamic CT findings were
visualized for surgically confirmed pelioid HCC. The dynamic CT finding for
the huge main mass was different from that of typical HCC in that initial
peripheral bright enhancement was equal to the attenuation of the adjacent
aorta. Another difference was that the enhancement progressed centrally,
mimicking centripetal enhancement. In contrast, the two adjacent daughter
nodules exhibited the typical enhancement patterns of HCC during dynamic
imaging: hyperattenuation, compared with the adjacent liver parenchyma, in the
hepatic arterial phase and isoattenuation or hypoattenuation in the portal
venous and delayed phases.
The two enhancement patterns of pelioid HCC can be explained on the basis
of their slightly different histologic features. At microscopic examination,
the mix of well-differentiated HCC cells and pelioid spaces was commonly found
in the peripheral zone of the main mass and in the two daughter nodules.
However, the relative proportion of pelioid spaces to cancer cell components
in the main mass was remarkably higher than in the daughter nodules. In the
main mass, the multifocal large pelioid spaces might have been responsible for
the gradual fill-in enhancement pattern, as in cavernous hemangioma. In
addition, the intervening thick tumor cellular components might have been
responsible for the scattered areas of low attenuation in the enhancing
portions, or they might have been a factor in diminishing the bright
enhancement of the pelioid space on the delayed phase images. In the two
daughter nodules, regardless of the pelioid spaces in these tumors, the
enhancement pattern was not different from that of typical HCC. This finding
can be explained on the basis of the relatively small proportions of pelioid
space compared with the spaces in the main mass, as was found in the
microscopic specimens.
In our case, the main mass should be differentiated from other hepatic
vascular tumors, especially cavernous hemangioma, which has a centripetal
enhancement pattern. Noticeable imaging features of the main mass suggested
HCC. Although the main mass exhibited progressive partial filling with
contrast material during dynamic imaging, minimal peripheral irregular
enhancement and multifocal areas of slightly lower attenuation in the bright
enhancing portion were visualized on arterial and delayed phase images,
respectively. These features may be used to differentiate the tumor from
typical hemangioma, which on delayed phase images exhibits early peripheral
globular enhancement and relatively homogeneous high attenuation of the
enhancing area relative to adjacent liver tissue, except for areas of
thrombosis, fibrosis, necrosis, hemorrhage, and cystic change
[7,
8]. These imaging features can
be explained by the presence of relatively thick layers of tumor cells that
intervened between the pelioid spaces rather than of the thin fibrous septa
usually seen in a typical hemangioma
[7]. Moreover, the cause of
capsule-like rim enhancement, a common findings in HCC, in the main mass on
delayed phase images proved to be a fibrotic capsule in the surgical
specimen.
To our knowledge, this case report is the first in the English-language
radiology literature to show the dynamic enhancing features of a pelioid HCC
on three-phase CT. The findings in this case indicate that the degree of
peliosis within HCC may be the main factor in determining the enhancement
pattern during the multiple dynamic phases. The abundant peliosis in this
tumor might have been responsible for the longer retention of contrast medium
and the resultant gradual fill-in enhancement during the dynamic phases, but
the presence of minimal peliosis had no noticeable effect on the typical
enhancement features of HCC. To arrive at a better definition of the specific
imaging findings of pelioid HCC, further evaluation with a large number of
pathologically proven cases is warranted.
References
- Semelka RC, Shoenut JP, Kroeker MA, et al. Focal liver disease:
comparison of dynamic contrast-enhanced CT and T2-weighted fat-suppressed,
FLASH, and dynamic gadolinium-enhanced MR imaging at 1.5 T.
Radiology 1992;184
: 687-694[Abstract/Free Full Text]
- Yoshimatsu S, Inoue Y, Ibukuro K, Suzuki S. Hypovascular
hepatocellular carcinoma undetected at angiography and CT with iodized oil.
Radiology 1989;171
: 343-347[Abstract/Free Full Text]
- Chedid A, Ryan LM, Dayal Y, Wolf BC, Falkson G. Morphology and
other prognostic factors of hepatocellular carcinoma. Arch Pathol
Lab Med 1999; 123:524
-528[Medline]
- Edmondson HA, Steiner PE. Primary carcinoma of liver: study of 100
cases among 48,900 necropsies. Cancer1954; 7:462
-503[CrossRef][Medline]
- Friedeman AC, Lichtenstein JE, Goodman Z, et al. Fibrolamellar
hepatocellular carcinoma. Radiology 1985;157
: 583-587[Abstract/Free Full Text]
- Ji EK, Ryu JS, Kang GH, Moon DH, Auh YH, Lee HK. Pelioid-type
hepatocellular carcinoma masquerading as a hepatic hemangioma on
technetium-99m red blood cell scintigraphy. Clin Nucl
Med 2001; 26:33
-35[CrossRef][Medline]
- Kew MC. Hepatic tumor and cysts. In: Feldman M, Scharschmidt BF,
Sleisenger MH, eds. Sleisenger and Fordtran's gastrointestinal and
liver disease, 6th ed. Philadelphia, PA: Saunders,1998
: 1364-1387
- Quinn SF, Benjamin GG. Hepatic cavernous hemangiomas: simple
diagnostic sign with dynamic bolus CT. Radiology1992; 182:545
-548[Abstract/Free Full Text]
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Introduction
Case Report
