(Radiographics. 2000;20:379-397.)
© RSNA, 2000
Imaging of Atypical Hemangiomas of the Liver with Pathologic Correlation1
Valérie Vilgrain, MD,
Leila Boulos, MD ,
Marie-Pierre Vullierme, MD ,
Alban Denys, MD ,
Benoît Terris, MD and
Yves Menu, MD
1 From the Departments of Radiology (V.V., L.B., M.P.V., A.D., Y.M.) and Pathology (B.T.), Hôpital Beaujon, 100 boulevard du Général Leclerc, 92118 Clichy, France. Presented as a scientific exhibit at the 1998 RSNA scientific assembly. Received June 9, 1999; revision requested July 9 and received August 9; accepted August 12. Address reprint requests to V.V. (e-mail: valerie.vilgrain@bjn.ap-hop-paris.fr).
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Abstract
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Compared with the imaging features of typical hepatic hemangiomas, the imaging features of atypical hepatic hemangiomas have not been well studied or well described. Knowledge of the entire spectrum of atypical hepatic hemangiomas is important and can help one avoid most diagnostic errors. A frequent type of atypical hepatic hemangioma is a lesion with an echoic border at ultrasonography. Less frequent types are large, heterogeneous hemangiomas; rapidly filling hemangiomas; calcified hemangiomas; hyalinized hemangiomas; cystic or multilocular hemangiomas; hemangiomas with fluid-fluid levels; and pedunculated hemangiomas. Adjacent abnormalities consist of arterial–portal venous shunt, capsular retraction, and surrounding nodular hyperplasia; hemangiomas can also develop in cases of fatty liver infiltration. Associated lesions include multiple hemangiomas, hemangiomatosis, focal nodular hyperplasia, and angiosarcoma. Types of atypical evolution are hemangiomas enlarging over time and hemangiomas appearing during pregnancy. Complications consist of inflammation, Kasabach-Merritt syndrome, intratumoral hemorrhage, hemoperitoneum, volvulus, and compression of adjacent structures. In some cases, such as large heterogeneous hemangiomas, calcified hemangiomas, pedunculated hemangiomas, or hemangiomas developing in diffuse fatty liver, a specific diagnosis can be established with imaging, especially magnetic resonance imaging. However, in other atypical cases, the diagnosis will remain uncertain at imaging, and these cases will require histopathologic examination.
Index Terms: Angioma, gastrointestinal tract, 761.3194 • Liver neoplasms, CT, 761.12112 • Liver neoplasms, diagnosis, 761.3194 • Liver neoplasms, MR, 761.121411, 761.12143 • Liver neoplasms, US, 761.12983
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Introduction
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Hemangioma is the most common benign hepatic tumor. The prevalence of hemangioma in the general population ranges from 1%–2% (1) to 20% (2); the female-to-male ratio varies from 2:1 to 5:1. Because hepatic hemangiomas are frequent, are most often asymptomatic, and have a very low rate of complications, this lesion does not require surgical resection. Therefore, the role of imaging is to help diagnose the lesion. In cases of typical hemangioma, imaging modalities are highly reliable for diagnosis, especially magnetic resonance (MR) imaging, which has a sensitivity and specificity of greater than 90% (1).
Conversely, the presence of atypical features in cases of hepatic hemangioma may lead to misdiagnosis and confusion with other lesions. In this article, we review the atypical features of hepatic hemangiomas. Specific topics discussed are typical hemangiomas, a frequent atypical pattern (hemangioma with echoic border), less frequent atypical patterns, atypical adjacent abnormalities, hemangioma in fatty liver infiltration, association with other lesions, atypical evolution, complications, biopsy, and differential diagnosis.
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Typical Hemangiomas
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The classic hemangioma is an asymptomatic lesion that is discovered at routine examination or autopsy. At ultrasonography (US), the typical appearance is a homogeneous, hyperechoic mass with well-defined margins and posterior acoustic enhancement (Fig 1a) (3).
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Figure 1a. Typical hemangioma. (a) Doppler US scan shows a homogeneous, hyperechoic lesion of the right hepatic lobe. No color signal is demonstrated. (b) Nonenhanced CT scan shows a hypoattenuating lesion of the right hepatic lobe. (c, d) Arterial-phase (c) and venous-phase (d) contrast material-enhanced CT scans show progressive, peripheral, globular enhancement, which is highly suggestive of hemangioma. (e) Delayed-phase CT scan shows that the lesion is isoattenuating relative to the liver, an appearance that suggests persistence of contrast material within the lesion.
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Figure 1b. Typical hemangioma. (a) Doppler US scan shows a homogeneous, hyperechoic lesion of the right hepatic lobe. No color signal is demonstrated. (b) Nonenhanced CT scan shows a hypoattenuating lesion of the right hepatic lobe. (c, d) Arterial-phase (c) and venous-phase (d) contrast material-enhanced CT scans show progressive, peripheral, globular enhancement, which is highly suggestive of hemangioma. (e) Delayed-phase CT scan shows that the lesion is isoattenuating relative to the liver, an appearance that suggests persistence of contrast material within the lesion.
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Figure 1c. Typical hemangioma. (a) Doppler US scan shows a homogeneous, hyperechoic lesion of the right hepatic lobe. No color signal is demonstrated. (b) Nonenhanced CT scan shows a hypoattenuating lesion of the right hepatic lobe. (c, d) Arterial-phase (c) and venous-phase (d) contrast material-enhanced CT scans show progressive, peripheral, globular enhancement, which is highly suggestive of hemangioma. (e) Delayed-phase CT scan shows that the lesion is isoattenuating relative to the liver, an appearance that suggests persistence of contrast material within the lesion.
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Figure 1d. Typical hemangioma. (a) Doppler US scan shows a homogeneous, hyperechoic lesion of the right hepatic lobe. No color signal is demonstrated. (b) Nonenhanced CT scan shows a hypoattenuating lesion of the right hepatic lobe. (c, d) Arterial-phase (c) and venous-phase (d) contrast material-enhanced CT scans show progressive, peripheral, globular enhancement, which is highly suggestive of hemangioma. (e) Delayed-phase CT scan shows that the lesion is isoattenuating relative to the liver, an appearance that suggests persistence of contrast material within the lesion.
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Figure 1e. Typical hemangioma. (a) Doppler US scan shows a homogeneous, hyperechoic lesion of the right hepatic lobe. No color signal is demonstrated. (b) Nonenhanced CT scan shows a hypoattenuating lesion of the right hepatic lobe. (c, d) Arterial-phase (c) and venous-phase (d) contrast material-enhanced CT scans show progressive, peripheral, globular enhancement, which is highly suggestive of hemangioma. (e) Delayed-phase CT scan shows that the lesion is isoattenuating relative to the liver, an appearance that suggests persistence of contrast material within the lesion.
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The computed tomographic (CT) findings consist of a hypoattenuating lesion on nonenhanced images (Fig 1b). After intravenous administration of contrast material, arterial-phase CT shows early, peripheral, globular enhancement of the lesion (Fig 1c). The attenuation of the peripheral nodules is equal to that of the adjacent aorta (4). Venous-phase CT shows centripetal enhancement that progresses to uniform filling (Fig 1d) (3,5). This enhancement persists on delayed-phase images (Fig 1e) (6).
At MR imaging, hemangiomas are characterized by well-defined margins and high signal intensity on T2-weighted images, which is identical to that of cerebrospinal fluid (6,7). Specificity is improved by using serial gadolinium-enhanced gradient-echo imaging (6). The gadolinium intake is similar to the intake of iodinated contrast material during enhanced CT. With T2-weighted spin-echo and dynamic gadolinium-enhanced T1-weighted gradient-echo sequences, the sensitivity and specificity of MR imaging are 98% and the accuracy is 99% (8).
Technetium-99m pertechnetate–labeled red blood cell scintigraphy is a relatively specific examination for diagnosis of hemangiomas. With this method, there is decreased activity on early dynamic images and increased activity on delayed blood pool images obtained over 30–50 minutes (3). Numerous studies have demonstrated that the sensitivity of single photon emission CT is superior to that of planar imaging; the former technique has a sensitivity of 78% and an accuracy of 80% (9). Therefore, radionuclide scintigraphy is a valuable tool when the diagnosis cannot be achieved with other imaging modalities. However, radionuclide scintigraphy for identification of hemangiomas is not performed routinely in all centers, especially outside the United States.
The imaging features of a hemangioma depend on its size; typical hemangiomas are mostly less than 3 cm in diameter (3).
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Frequent Atypical Pattern: Hemangioma with Echoic Border
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An atypical but suggestive appearance of hemangiomas at US is the following: The lesion has an echoic border, which is seen as a thick echoic rind or a thin echoic rim (1). Unlike typical hemangiomas, this type of hemangioma has an internal echo pattern that is at least partially hypoechoic (Fig 2). The central low echogenicity is assumed to correspond to previous hemorrhagic necrosis, scarring, or myxomatous changes. The corresponding CT and MR imaging appearances of hemangiomas with echoic borders are not precisely described in the literature; in most such cases, we have observed typical patterns at CT or MR imaging.
Although the real percentage is unknown, some authors have reported that 40% of all hemangiomas could have this atypia (1).
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Less Frequent Atypical Patterns
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Large, Heterogeneous Hemangioma
Large hemangiomas are often heterogeneous (10). They are termed giant hemangiomas when they exceed 4 cm in diameter (3,11). However, some authors define giant hemangiomas as lesions greater than 6 cm (12) or 12 cm (13) in diameter. Large hemangiomas may be responsible for liver enlargement and abdominal discomfort.
At US, large hemangiomas often appear heterogeneous (Fig 3a).
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Figure 3a. Large, heterogeneous hemangioma. (a) US scan of the liver shows a large, heterogeneous lesion with a hypoechoic center. (b) Nonenhanced CT scan shows a hypoattenuating lesion with a markedly hypoattenuating center. (c) Contrast-enhanced CT scan shows the typical enhancement pattern of hemangioma. (d) Delayed-phase CT scan shows incomplete filling of the lesion. (e) T1-weighted spin-echo MR image shows a markedly hypointense center and some hypointense linear elements within a hypointense lesion. (f) T2-weighted spin-echo MR image shows that the lesion is hyperintense relative to the liver with a markedly hyperintense center. Note the hypointense linear elements, which correspond to internal septa.
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Figure 3b. Large, heterogeneous hemangioma. (a) US scan of the liver shows a large, heterogeneous lesion with a hypoechoic center. (b) Nonenhanced CT scan shows a hypoattenuating lesion with a markedly hypoattenuating center. (c) Contrast-enhanced CT scan shows the typical enhancement pattern of hemangioma. (d) Delayed-phase CT scan shows incomplete filling of the lesion. (e) T1-weighted spin-echo MR image shows a markedly hypointense center and some hypointense linear elements within a hypointense lesion. (f) T2-weighted spin-echo MR image shows that the lesion is hyperintense relative to the liver with a markedly hyperintense center. Note the hypointense linear elements, which correspond to internal septa.
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Figure 3c. Large, heterogeneous hemangioma. (a) US scan of the liver shows a large, heterogeneous lesion with a hypoechoic center. (b) Nonenhanced CT scan shows a hypoattenuating lesion with a markedly hypoattenuating center. (c) Contrast-enhanced CT scan shows the typical enhancement pattern of hemangioma. (d) Delayed-phase CT scan shows incomplete filling of the lesion. (e) T1-weighted spin-echo MR image shows a markedly hypointense center and some hypointense linear elements within a hypointense lesion. (f) T2-weighted spin-echo MR image shows that the lesion is hyperintense relative to the liver with a markedly hyperintense center. Note the hypointense linear elements, which correspond to internal septa.
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Figure 3d. Large, heterogeneous hemangioma. (a) US scan of the liver shows a large, heterogeneous lesion with a hypoechoic center. (b) Nonenhanced CT scan shows a hypoattenuating lesion with a markedly hypoattenuating center. (c) Contrast-enhanced CT scan shows the typical enhancement pattern of hemangioma. (d) Delayed-phase CT scan shows incomplete filling of the lesion. (e) T1-weighted spin-echo MR image shows a markedly hypointense center and some hypointense linear elements within a hypointense lesion. (f) T2-weighted spin-echo MR image shows that the lesion is hyperintense relative to the liver with a markedly hyperintense center. Note the hypointense linear elements, which correspond to internal septa.
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Figure 3e. Large, heterogeneous hemangioma. (a) US scan of the liver shows a large, heterogeneous lesion with a hypoechoic center. (b) Nonenhanced CT scan shows a hypoattenuating lesion with a markedly hypoattenuating center. (c) Contrast-enhanced CT scan shows the typical enhancement pattern of hemangioma. (d) Delayed-phase CT scan shows incomplete filling of the lesion. (e) T1-weighted spin-echo MR image shows a markedly hypointense center and some hypointense linear elements within a hypointense lesion. (f) T2-weighted spin-echo MR image shows that the lesion is hyperintense relative to the liver with a markedly hyperintense center. Note the hypointense linear elements, which correspond to internal septa.
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Figure 3f. Large, heterogeneous hemangioma. (a) US scan of the liver shows a large, heterogeneous lesion with a hypoechoic center. (b) Nonenhanced CT scan shows a hypoattenuating lesion with a markedly hypoattenuating center. (c) Contrast-enhanced CT scan shows the typical enhancement pattern of hemangioma. (d) Delayed-phase CT scan shows incomplete filling of the lesion. (e) T1-weighted spin-echo MR image shows a markedly hypointense center and some hypointense linear elements within a hypointense lesion. (f) T2-weighted spin-echo MR image shows that the lesion is hyperintense relative to the liver with a markedly hyperintense center. Note the hypointense linear elements, which correspond to internal septa.
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On nonenhanced CT scans, lesions appear hypoattenuating and heterogeneous with marked central areas of low attenuation (Fig 3b). After intravenous administration of contrast material, the typical early, peripheral, globular enhancement is observed (Fig 3c). However, during the venous and delayed phases, the progressive centripetal enhancement of the lesion, although present, does not lead to complete filling (Fig 3d).
At MR imaging, T1-weighted sequences show a sharply marginated, hypointense mass with a cleftlike area of lower intensity and sometimes with hypointense internal septa (Fig 3e). T2-weighted images show a markedly hyperintense cleftlike area and some hypointense internal septa within a hyperintense mass (Fig 3f) (7). The enhancement is equivalent to that seen at CT, with incomplete filling of the lesion; the cleftlike area remains hypointense, as do the internal septa (12).
The MR imaging findings of giant hemangiomas are closely correlated with the macroscopic appearance, which demonstrates changes such as hemorrhage, thrombosis, extensive hyalinization, liquefaction, and fibrosis. The central cleftlike area may be due to cystic degeneration or liquefaction (12). The internal septa may correspond to poorly cellular fibrous tissue (12).
Rapidly Filling Hemangioma
Rapidly filling hemangiomas are not very frequent (16% of all hemangiomas). However, rapid filling seems to occur significantly more often in small hemangiomas (42% of hemangiomas <1 cm in diameter) (14).
CT and MR imaging show a particular enhancement pattern: immediate homogeneous enhancement at arterial-phase CT or contrast-enhanced T1-weighted MR imaging (Fig 4a) (2). This feature makes differentiation from other hypervascular tumors difficult. T2-weighted images may be helpful, but hypervascular tumors such as islet cell metastases are also hyperintense on such images.
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Figure 4a. Rapidly filling hemangioma. (a) Early-phase T1-weighted MR image shows immediate homogeneous enhancement of a small lesion (arrow). (b) Delayed-phase T1-weighted MR image shows persistent enhancement of the lesion. The diagnosis was proved with biopsy.
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Figure 4b. Rapidly filling hemangioma. (a) Early-phase T1-weighted MR image shows immediate homogeneous enhancement of a small lesion (arrow). (b) Delayed-phase T1-weighted MR image shows persistent enhancement of the lesion. The diagnosis was proved with biopsy.
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Accurate diagnosis is made with delayed-phase CT or MR imaging because hemangiomas remain hyperattenuating or hyperintense, whereas hypervascular metastases do not (Fig 4b). Another important finding in diagnosis of hemangioma is attenuation equivalent to that of the aorta during all phases of CT (4). At Doppler US, unusual arterial flow may be present.
Because histopathologic confirmation is usually not performed, the mechanism of the enhancement is not clearly understood; however, the difference in enhancement patterns may be due to a difference in the size of the blood spaces. It is likely that the smaller the lesion, the more rapid is the spread of contrast material within it (14). This theory could explain the high proportion of small hemangiomas with rapid and complete filling.
Calcified Hemangioma
Although hemangiomas in the soft tissue, gastrointestinal tract, retroperitoneum, and mediastinum may show calcifications (phleboliths, which are pathognomonic for the tumor), hepatic hemangiomas rarely demonstrate calcifications (15, 16). Calcified hemangiomas are mostly found incidentally.
Calcifications may occur in the marginal or central portion of the lesion (Fig 5) (17). A particular pattern consists of multiple spotty calcifications, which correspond to phleboliths (Fig 6) (17). However, large, organized calcifications are also possible. Some calcified hemangiomas may demonstrate poor enhancement, especially at CT (17).
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Figure 5a. Calcified hemangioma. (a) US scan of the liver shows an isoechoic lesion with a large calcification. (b, c) Arterial-phase (b) and venous-phase (c) contrast-enhanced CT scans show a large calcification within a hypoattenuating lesion. (d) T2-weighted MR image shows that the lesion is isointense relative to cerebrospinal fluid; the large central area of low signal intensity corresponds to the calcification. The diagnosis was proved with pathologic examination after surgical resection.
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Figure 5b. Calcified hemangioma. (a) US scan of the liver shows an isoechoic lesion with a large calcification. (b, c) Arterial-phase (b) and venous-phase (c) contrast-enhanced CT scans show a large calcification within a hypoattenuating lesion. (d) T2-weighted MR image shows that the lesion is isointense relative to cerebrospinal fluid; the large central area of low signal intensity corresponds to the calcification. The diagnosis was proved with pathologic examination after surgical resection.
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Figure 5c. Calcified hemangioma. (a) US scan of the liver shows an isoechoic lesion with a large calcification. (b, c) Arterial-phase (b) and venous-phase (c) contrast-enhanced CT scans show a large calcification within a hypoattenuating lesion. (d) T2-weighted MR image shows that the lesion is isointense relative to cerebrospinal fluid; the large central area of low signal intensity corresponds to the calcification. The diagnosis was proved with pathologic examination after surgical resection.
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Figure 5d. Calcified hemangioma. (a) US scan of the liver shows an isoechoic lesion with a large calcification. (b, c) Arterial-phase (b) and venous-phase (c) contrast-enhanced CT scans show a large calcification within a hypoattenuating lesion. (d) T2-weighted MR image shows that the lesion is isointense relative to cerebrospinal fluid; the large central area of low signal intensity corresponds to the calcification. The diagnosis was proved with pathologic examination after surgical resection.
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Figure 6. Calcified hemangioma. Nonenhanced CT scan shows an ill-defined lesion of the right hepatic lobe with multiple spotty calcifications. The diagnosis was proved with surgical biopsy.
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The finding of a nonenhancing hepatic tumor with calcifications should not preclude the diagnosis of hemangioma. High signal intensity in noncalcified areas of the lesion on T2-weighted MR images can help in diagnosis (Fig 5d).
Hyalinized Hemangioma
Hyalinized hepatic hemangiomas are rare (18,19). Some authors have suggested that hyalinized hemangiomas represent an end stage of hemangioma involution. Such hemangiomas do not demonstrate any particular symptoms.
Hyalinization of a hemangioma changes its radiologic features, thus making diagnosis before biopsy virtually impossible. Whereas typical hemangiomas are characterized by marked high signal intensity on T2-weighted MR images, hyalinized hemangiomas show only slight high signal intensity (18).
Moreover, there is lack of early enhancement on dynamic contrast-enhanced images (Fig 7a) (7,20). Slight peripheral enhancement may occur in the late phase (Fig 7b) (18). MR imaging does not allow differentiation of hyalinized hemangiomas from malignant hepatic tumors (Fig 7c).
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Figure 7a. Hyalinized hemangioma. (a) Contrast-enhanced CT scan shows a large, hypoattenuating lesion in segment VII. (b) Delayed-phase CT scan shows heterogeneous uptake of contrast material by the lesion. (c) T2-weighted spin-echo MR image shows that the lesion is heterogeneous and less hyperintense than cerebrospinal fluid. (d) Photograph of the pathologic specimen shows extensive fibrosis within the lesion.
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Figure 7b. Hyalinized hemangioma. (a) Contrast-enhanced CT scan shows a large, hypoattenuating lesion in segment VII. (b) Delayed-phase CT scan shows heterogeneous uptake of contrast material by the lesion. (c) T2-weighted spin-echo MR image shows that the lesion is heterogeneous and less hyperintense than cerebrospinal fluid. (d) Photograph of the pathologic specimen shows extensive fibrosis within the lesion.
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Figure 7c. Hyalinized hemangioma. (a) Contrast-enhanced CT scan shows a large, hypoattenuating lesion in segment VII. (b) Delayed-phase CT scan shows heterogeneous uptake of contrast material by the lesion. (c) T2-weighted spin-echo MR image shows that the lesion is heterogeneous and less hyperintense than cerebrospinal fluid. (d) Photograph of the pathologic specimen shows extensive fibrosis within the lesion.
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Figure 7d. Hyalinized hemangioma. (a) Contrast-enhanced CT scan shows a large, hypoattenuating lesion in segment VII. (b) Delayed-phase CT scan shows heterogeneous uptake of contrast material by the lesion. (c) T2-weighted spin-echo MR image shows that the lesion is heterogeneous and less hyperintense than cerebrospinal fluid. (d) Photograph of the pathologic specimen shows extensive fibrosis within the lesion.
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Pathologic examination reveals extensive fibrous tissue (Fig 7d) (7,20) and obliteration of vascular channels (18). These findings are responsible for the decreased signal intensity on T2-weighted MR images and for the lack of enhancement, respectively. Percutaneous biopsy is indicated in these cases (18).
Cystic or Multilocular Hemangioma
Cavernous hemangiomas with a large central cavity that contains fluid are very rare (21). To our knowledge, only one hemangioma with a multilocular cystic component has been reported in the literature (22). This entity does not demonstrate any particular symptoms.
US can show a nonspecific lesion with a central fluid-filled component, which is sometimes multilocular. CT may show some degree of peripheral enhancement; the cystic component does not enhance. On MR images, the lesion appears as one or several fluid-filled cavities, which are sometimes associated with peripheral enhancement.
Definite diagnosis of such hemangiomas with imaging is difficult. This atypia may be due to cystic degeneration caused by central thrombosis and hemorrhage.
Hemangioma with Fluid-Fluid Level
Fluid-fluid levels within hemangiomas are very rare. To our knowledge, only three articles on this entity have been published (23–25). The patient may present with abdominal pain.
US shows a hyperechoic or hypoechoic pattern. The fluid-fluid level is not seen at US (23–25).
CT and especially MR imaging easily demonstrate this feature. Stagnant blood may be responsible for the sedimentation effect at CT and MR imaging, with the superior fluid layer consisting of unclotted serous blood and the inferior fluid layer consisting of red blood cells. The superior layer is hypoattenuating on CT scans, isointense to muscle on T1-weighted MR images, and markedly hyperintense on T2-weighted MR images. The inferior layer is of higher attenuation on CT scans, hyperintense to muscle on T1-weighted images, and slightly hyperintense on T2-weighted images (Fig 8) (25).
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Figure 8. Hemangioma with fluid-fluid level. T2-weighted spin-echo MR image shows a lesion with a fluid-fluid level (arrowheads). The inferior fluid layer is hypointense relative to the superior fluid layer. (Courtesy of Philippe Soyer, MD, PhD, Hôpital Lariboisière, Paris, France.)
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Nevertheless, fluid-fluid levels in hepatic lesions do not indicate a specific diagnosis and can be observed in both malignant and benign conditions (25). Some authors have suggested that fluid-fluid levels that are clearly demonstrated with CT or MR imaging but not visible at US could be suggestive of hemangioma (24).
Pathologic correlation shows that fluid-fluid levels in hemangiomas correspond to the sedimentation effect within a large vascular space (25). Histologic examination may be required for diagnosis.
Pedunculated Hemangioma
Pedunculated hemangiomas are very rare. To our knowledge, only two cases have been reported in the literature (26,27). They can be asymptomatic or complicated by subacute torsion and infarction.
At US, the origin of the lesion may be difficult to recognize. The lesion can be attached to the liver by a thin pedicle, which is nearly undetectable at imaging. Multiplanar reconstruction of CT scans and coronal or sagittal MR imaging can be helpful. At CT and MR imaging, the diagnosis is made by demonstrating the typical enhancement pattern and the typical signal intensities on both T1- and T2-weighted images (Fig 9).
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Figure 9. Pedunculated hemangioma. Contrast-enhanced CT scan shows a pedunculated hemangioma (arrowheads). The connection of the hemangioma to the liver was seen on a more cranial section. The diagnosis was suggested by the typical enhancement pattern and the typical MR imaging features.
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Pathologic examination is usually not required. Complicated pedunculated hemangiomas must be resected immediately.
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Atypical Adjacent Abnormalities
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Hemangioma with Arterial–Portal Venous Shunt
Arterial–portal venous shunts are mainly associated with hepatic malignancy but can also be seen in benign liver masses (28,29), in particular hemangiomas. Fourteen cases of hemangiomas with arterial–portal venous shunts are reported in the literature. This entity is usually asymptomatic.
An arterial–portal venous shunt can be detected with helical CT or dynamic contrast-enhanced MR imaging (Fig 10). The findings consist of early parenchymal enhancement (14) associated with early filling of the portal vein.
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Figure 10a. Hemangioma with arterial-portal venous shunt. (a) Arterial-phase CT scan shows early peripheral enhancement of a hypoattenuating lesion of segment IV. Note the filling of the right portal vein (arrows). (b) Arterial-phase T1-weighted gradient-echo MR image shows early filling of the right portal vein (arrows). (c) Selective hepatic angiogram shows irregular enhancement of the lesion associated with early opacification of the right portal vein (arrows). (d) Photograph of the resected specimen shows the hemangioma.
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Figure 10b. Hemangioma with arterial-portal venous shunt. (a) Arterial-phase CT scan shows early peripheral enhancement of a hypoattenuating lesion of segment IV. Note the filling of the right portal vein (arrows). (b) Arterial-phase T1-weighted gradient-echo MR image shows early filling of the right portal vein (arrows). (c) Selective hepatic angiogram shows irregular enhancement of the lesion associated with early opacification of the right portal vein (arrows). (d) Photograph of the resected specimen shows the hemangioma.
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Figure 10c. Hemangioma with arterial-portal venous shunt. (a) Arterial-phase CT scan shows early peripheral enhancement of a hypoattenuating lesion of segment IV. Note the filling of the right portal vein (arrows). (b) Arterial-phase T1-weighted gradient-echo MR image shows early filling of the right portal vein (arrows). (c) Selective hepatic angiogram shows irregular enhancement of the lesion associated with early opacification of the right portal vein (arrows). (d) Photograph of the resected specimen shows the hemangioma.
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Figure 10d. Hemangioma with arterial-portal venous shunt. (a) Arterial-phase CT scan shows early peripheral enhancement of a hypoattenuating lesion of segment IV. Note the filling of the right portal vein (arrows). (b) Arterial-phase T1-weighted gradient-echo MR image shows early filling of the right portal vein (arrows). (c) Selective hepatic angiogram shows irregular enhancement of the lesion associated with early opacification of the right portal vein (arrows). (d) Photograph of the resected specimen shows the hemangioma.
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Hemangioma with Capsular Retraction
Capsular retraction is usually associated with malignant tumors such as cholangiocarcinoma, epithelioid hemangioendothelioma, or metastases. We have seen one case of hemangioma associated with capsular retraction (Fig 11), which was diagnosed by means of surgical biopsy and absence of change over time.
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Figure 11. Hemangioma with capsular retraction. T2-weighted MR image shows a markedly hyperintense lesion in segments IV and VIII with capsular retraction (arrow). The diagnosis was proved with surgical biopsy and follow-up for 8 years.
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A possible mechanism could be fibrous degeneration. However, in our case, the high signal intensity on T2-weighted MR images and the histopathologic findings were not suggestive of a fibrous component.
Nodular Hyperplasia Surrounding Hemangioma
Regenerative nodular hyperplasia has been reported at the periphery of hypervascular tumors such as fibrolamellar carcinoma (30).
We have seen one case of regenerative nodular hyperplasia surrounding a hepatic hemangioma; to our knowledge, this finding has not been reported in the literature. At imaging, the central part of the lesion was similar to that of a typical hemangioma and the peripheral part enhanced homogeneously on arterial-phase CT and MR images, producing a rimlike appearance (Fig 12). Pathologic examination revealed a typical hemangioma surrounded by a fleshy, tan rim 1–2 cm thick.
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Figure 12a. Nodular hyperplasia surrounding hemangioma. (a, b) Contrast-enhanced CT scan (a) and contrast-enhanced T1-weighted gradient-echo MR image (b) show a lesion with continuous peripheral enhancement (arrowheads). Note the enhancement of the adjacent parenchyma (arrows). (c) T2-weighted spin-echo MR image shows a homogeneous, hyperintense lesion. Pathologic examination after surgical resection revealed a hemangioma surrounded by regenerative nodular hyperplasia.
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Figure 12b. Nodular hyperplasia surrounding hemangioma. (a, b) Contrast-enhanced CT scan (a) and contrast-enhanced T1-weighted gradient-echo MR image (b) show a lesion with continuous peripheral enhancement (arrowheads). Note the enhancement of the adjacent parenchyma (arrows). (c) T2-weighted spin-echo MR image shows a homogeneous, hyperintense lesion. Pathologic examination after surgical resection revealed a hemangioma surrounded by regenerative nodular hyperplasia.
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Figure 12c. Nodular hyperplasia surrounding hemangioma. (a, b) Contrast-enhanced CT scan (a) and contrast-enhanced T1-weighted gradient-echo MR image (b) show a lesion with continuous peripheral enhancement (arrowheads). Note the enhancement of the adjacent parenchyma (arrows). (c) T2-weighted spin-echo MR image shows a homogeneous, hyperintense lesion. Pathologic examination after surgical resection revealed a hemangioma surrounded by regenerative nodular hyperplasia.
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The arterial supply is thought to be derived from the tumor vasculature; this theory may explain the development of parenchymal hyperplasia (30). Although the association with regenerative nodular hyperplasia is very rare, it does not rule out the diagnosis of hemangioma. Furthermore, if biopsy is needed, awareness of this phenomenon allows one to avoid false-negative results due to sampling of the regenerative area.
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Hemangioma in Fatty Liver Infiltration
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Diffuse fatty infiltration of the liver is a common finding and may change the typical appearances of lesions, making them more difficult to characterize at imaging.
At US, a hemangioma may appear slightly hyperechoic, isoechoic, or hypoechoic relative to a fatty liver (31). Posterior acoustic enhancement is usually observed.
At nonenhanced CT, the lesion may be hyperattenuating relative to the liver (Fig 13a) or may not be seen. Contrast-enhanced CT shows peripheral enhancement and delayed filling, an appearance similar to that of a hemangioma in a normal liver (Fig 13b, 13c) (32). However, at arterial-phase imaging, the hemangioma may be isoattenuating relative to the liver (Fig 13b).
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Figure 13a. Hemangioma in a fatty liver. (a) Nonenhanced CT scan shows multiple hyperattenuating lesions in a hypoattenuating fatty liver parenchyma. (b) Arterial-phase CT scan shows that the lesions are mostly isoattenuating relative to the liver. (c) Portal-phase CT scan shows enhancement of the lesions. (d) T2-weighted MR image shows typical hemangiomas. The diagnosis was suggested by the typical enhancement pattern and the typical MR imaging features.
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Figure 13b. Hemangioma in a fatty liver. (a) Nonenhanced CT scan shows multiple hyperattenuating lesions in a hypoattenuating fatty liver parenchyma. (b) Arterial-phase CT scan shows that the lesions are mostly isoattenuating relative to the liver. (c) Portal-phase CT scan shows enhancement of the lesions. (d) T2-weighted MR image shows typical hemangiomas. The diagnosis was suggested by the typical enhancement pattern and the typical MR imaging features.
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Figure 13c. Hemangioma in a fatty liver. (a) Nonenhanced CT scan shows multiple hyperattenuating lesions in a hypoattenuating fatty liver parenchyma. (b) Arterial-phase CT scan shows that the lesions are mostly isoattenuating relative to the liver. (c) Portal-phase CT scan shows enhancement of the lesions. (d) T2-weighted MR image shows typical hemangiomas. The diagnosis was suggested by the typical enhancement pattern and the typical MR imaging features.
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Figure 13d. Hemangioma in a fatty liver. (a) Nonenhanced CT scan shows multiple hyperattenuating lesions in a hypoattenuating fatty liver parenchyma. (b) Arterial-phase CT scan shows that the lesions are mostly isoattenuating relative to the liver. (c) Portal-phase CT scan shows enhancement of the lesions. (d) T2-weighted MR image shows typical hemangiomas. The diagnosis was suggested by the typical enhancement pattern and the typical MR imaging features.
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MR imaging is more helpful than CT and allows reliable detection and differentiation of hemangiomas from other hepatic masses (Fig 13d) (33).
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Association with Other Lesions
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Multiple Hemangiomas
Hemangiomas are multiple in 10% of cases (34). Multiple hemangiomas generally consist of a few scattered lesions (10). They often have typical imaging features (Fig 14).
Hemangiomatosis
Hemangiomas, even giant ones, are usually well defined (11). In rare cases, the lesion may be large and ill defined, replacing almost the whole hepatic parenchyma. This entity is seen more often in infants than in adults and may be associated with cardiac failure and high mortality. In adults, hemangiomatosis can be asymptomatic.
US demonstrates large, hypoechoic masses with ill-defined margins to the normal parenchyma (Fig 15a) (11). Numerous confluent hyperechoic masses are also observed (35). At CT, the typical peripheral enhancement may be lacking (11); the most suggestive feature is delayed enhancement (Fig 15b–15d). MR imaging enables correct diagnosis by demonstrating characteristic signal intensities on both T1- and T2-weighted images (Fig 15e).
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Figure 15a. Hemangiomatosis. (a) US scan of the liver shows large, ill-defined, hypoechoic areas. (b) Nonenhanced CT scan shows large, hypoattenuating areas. (c) Early-phase CT scan shows enhancement of only the normal parenchyma (arrows). (d) Delayed-phase CT scan shows that the liver is homogeneous because the hemangiomas have enhanced. (e) T2-weighted spin-echo MR image shows marked ill-defined high signal intensity, which corresponds to hemangiomatosis. The diagnosis was proved with surgical biopsy.
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Figure 15b. Hemangiomatosis. (a) US scan of the liver shows large, ill-defined, hypoechoic areas. (b) Nonenhanced CT scan shows large, hypoattenuating areas. (c) Early-phase CT scan shows enhancement of only the normal parenchyma (arrows). (d) Delayed-phase CT scan shows that the liver is homogeneous because the hemangiomas have enhanced. (e) T2-weighted spin-echo MR image shows marked ill-defined high signal intensity, which corresponds to hemangiomatosis. The diagnosis was proved with surgical biopsy.
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Figure 15c. Hemangiomatosis. (a) US scan of the liver shows large, ill-defined, hypoechoic areas. (b) Nonenhanced CT scan shows large, hypoattenuating areas. (c) Early-phase CT scan shows enhancement of only the normal parenchyma (arrows). (d) Delayed-phase CT scan shows that the liver is homogeneous because the hemangiomas have enhanced. (e) T2-weighted spin-echo MR image shows marked ill-defined high signal intensity, which corresponds to hemangiomatosis. The diagnosis was proved with surgical biopsy.
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Figure 15d. Hemangiomatosis. (a) US scan of the liver shows large, ill-defined, hypoechoic areas. (b) Nonenhanced CT scan shows large, hypoattenuating areas. (c) Early-phase CT scan shows enhancement of only the normal parenchyma (arrows). (d) Delayed-phase CT scan shows that the liver is homogeneous because the hemangiomas have enhanced. (e) T2-weighted spin-echo MR image shows marked ill-defined high signal intensity, which corresponds to hemangiomatosis. The diagnosis was proved with surgical biopsy.
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Abstract
Introduction
