(Radiographics. 1999;19:1689-1692.)
© RSNA, 1999
US Case of the Day1
Ramesh Avva, MD,
Hemendra R. Shah, MD and
Teresita L. Angtuaco, MD
1 From the Department of Radiology, University of Arkansas for Medical Sciences, 4301 W Markham St, Little Rock, AR 72205. Received November 20, 1998; revision requested December 10 and received February 5, 1999; accepted February 8. Address reprint requests to T.L.A.
Index Terms: Angioma, 761.3194 • Liver neoplasms, diagnosis, 761.3194
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HISTORY
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A 60-year-old woman presented to the emergency department with a 1-week history of night sweating, fevers, and chills. She also had a 3-day history of nonradiating abdominal pain in the right upper quadrant and intermittent nausea without vomiting. Initial laboratory results showed mild elevation of liver enzyme levels: aspartate aminotransferase, 55 U/L; alanine aminotransferase, 118 U/L; 
-glutamyl transferase, 84 U/L; and alkaline phosphatase, 194 U/L. The medical history, physical examination results, and other laboratory data were unremarkable. Abdominal ultrasonography (US) was performed.
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FINDINGS
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In the superior aspect of the left lobe of the liver, a 6 x 8 x 5.5-cm, hyperechoic mass with central areas of decreased echogenicity was identified (Fig 1). In the inferior aspect of the medial segment of the left lobe, a more complex mass measuring 5 x 9 x 10.4 cm was seen (Fig 2). The periphery of the mass was slightly hyperechoic relative to the adjacent liver tissue, but the central and posterior portions of the mass were hypoechoic. Both masses distorted the liver border. At color Doppler US, no vascularity was seen within either mass. Longitudinal US demonstrated the relationship between the masses (Fig 3). No other masses or abnormalities were identified in the rest of the abdomen. Subsequently, computed tomography (CT) and nuclear medicine imaging were performed.
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Figures 1-3. (1) Transverse US image of the liver shows a large, hyperechoic lesion distorting the medial border of the left lobe (arrow). A small central area of decreased echogenicity is seen. (2) Longitudinal US image of the liver shows a larger mass with more complex characteristics inferior to the lesion seen in The periphery of the mass is hyperechoic, but the central and posterior portions are hypoechoic. (3) Longitudinal US image of the liver shows the relationship between the superior mass (arrow) and the inferior mass (arrowhead). The inclusion of both masses in a single image allows better appreciation of the differences in their imaging characteristics.
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Figures 1-3. (1) Transverse US image of the liver shows a large, hyperechoic lesion distorting the medial border of the left lobe (arrow). A small central area of decreased echogenicity is seen. (2) Longitudinal US image of the liver shows a larger mass with more complex characteristics inferior to the lesion seen in The periphery of the mass is hyperechoic, but the central and posterior portions are hypoechoic. (3) Longitudinal US image of the liver shows the relationship between the superior mass (arrow) and the inferior mass (arrowhead). The inclusion of both masses in a single image allows better appreciation of the differences in their imaging characteristics.
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Figures 1-3. (1) Transverse US image of the liver shows a large, hyperechoic lesion distorting the medial border of the left lobe (arrow). A small central area of decreased echogenicity is seen. (2) Longitudinal US image of the liver shows a larger mass with more complex characteristics inferior to the lesion seen in The periphery of the mass is hyperechoic, but the central and posterior portions are hypoechoic. (3) Longitudinal US image of the liver shows the relationship between the superior mass (arrow) and the inferior mass (arrowhead). The inclusion of both masses in a single image allows better appreciation of the differences in their imaging characteristics.
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DIAGNOSIS: Giant hemangiomas of the liver.
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DISCUSSION
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Hemangiomas are the most common primary liver tumor. They occur much more commonly in female patients (female-to-male ratio, 4–5:1) and are typically asymptomatic. However, abdominal pain and discomfort may develop if compression of adjacent structures, thrombosis, or hemorrhage occurs (1). Although hemangiomas commonly are stable in size or show minimal growth, they can show significant enlargement (2). Hemangiomas may enlarge during pregnancy and are commonly present in other organs. Large hemangiomas may be associated with consumption coagulopathy; this condition is called the Kasabach-Merritt syndrome. At pathologic analysis, hemangiomas are blood-filled spaces without normal intervening hepatic parenchyma; the spaces are lined with a single layer of endothelial cells. Thrombosis of vascular channels may lead to areas of calcification, fibrosis, and scarring. The term giant hemangioma has been used to describe lesions larger than 4–10 cm in diameter (1,2). Although this term is seen in the radiology literature, the pathology literature does not make this distinction.
Hemangiomas have been shown to be present in 5%–20% of patients in various autopsy series. Because of this frequency, they are often encountered during routine US or CT examinations of the abdomen performed for other reasons. Therefore, an appreciation of the characteristic US and CT features of hemangioma is important.
At US, hemangiomas typically appear as well-defined, homogeneous, hyperechoic lesions (3). Posterior wall enhancement may or may not be present. Although this appearance is characteristic, it is not specific for hemangioma. Lesions such as hepatocellular carcinoma, hypervascular metastases, and focal nodular hyperplasia may have similar findings. Also, this appearance applies to small lesions (<3 cm in diameter). In larger lesions, increased heterogeneity is frequently present due to areas of vessel thrombosis and fibrosis. In these cases, US may reveal a mass with a hypoechoic central portion, whereas the periphery remains hyperechoic. Furthermore, if a patient has fatty infiltration of the liver, a hemangioma may be hypoechoic because of the increased background echogenicity of the liver (4).
Originally, single-level dynamic CT was used for diagnosing liver hemangiomas. However, this technique could be performed only if a suspected lesion was demonstrated at previous CT or US. On nonenhanced images, hemangiomas were hypoattenuating. Dynamic CT after administration of a contrast material bolus showed peripheral enhancement and demonstrated gradual filling of the lesion until it was isoattenuating to the liver parenchyma on delayed images (5). Strict interpretation of these criteria led to high specificity in the diagnosis of hemangiomas. However, only 55% of hemangiomas fulfilled all of these criteria in one study (5). Other appearances were often encountered. Small lesions sometimes enhanced homogeneously and rapidly, whereas some larger lesions never demonstrated complete filling. The discrepancy in the enhancement pattern of hemangiomas may be related to the size of the vascular spaces within the lesion (6).
Often, contrast-enhanced single-pass CT of the abdomen may incidentally demonstrate hemangiomas of the liver without the benefit of nonenhanced or delayed images to aid interpretation. In these cases, careful evaluation of the enhancement pattern is helpful in making the correct diagnosis. Hemangiomas characteristically show globular discontinuous areas of enhancement along their periphery with an attenuation similar to that of the aorta (7) (Fig 4). No metastases exhibited this enhancement pattern in the series of Leslie et al (7). However, this pattern was seen in only two-thirds of cases. Other enhancement patterns such as ring enhancement or combined central and peripheral enhancement were seen in both hemangiomas and malignant lesions (Fig 5).
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Figures 4, 5. (4) Contrast-enhanced CT scan of the liver shows the superior mass in the lateral segment of the left lobe. Note the nodular peripheral enhancement, which is suggestive of a hemangioma. (5) Contrast-enhanced CT scan of the liver shows the inferior mass along the inferior margin of the left lobe with more intense peripheral enhancement. The larger hypoattenuating central area suggests that there is more internal degeneration within this mass.
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Figures 4, 5. (4) Contrast-enhanced CT scan of the liver shows the superior mass in the lateral segment of the left lobe. Note the nodular peripheral enhancement, which is suggestive of a hemangioma. (5) Contrast-enhanced CT scan of the liver shows the inferior mass along the inferior margin of the left lobe with more intense peripheral enhancement. The larger hypoattenuating central area suggests that there is more internal degeneration within this mass.
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Lesions detected at US or CT that are highly suggestive of hemangioma are often reexamined in 3–6 months to assess for lesion stability. However, if the findings of these studies are atypical or if there is concern about possible metastatic disease, patients are often referred for red blood cell scintigraphy or magnetic resonance (MR) imaging for more definitive evaluation.
At red blood cell scintigraphy, hemangiomas classically demonstrate decreased activity on perfusion images and increased activity on delayed or blood pool images (8) (Fig 6). The specificity of red blood cell scintigraphy in the detection of hemangioma approaches 100% with very few false-positive cases reported (9). These false-positive cases have been secondary to hemangiosarcomas or atypical cases of hepatocellular carcinoma, metastatic colon cancer, or metastatic carcinoid tumor. Rarely, hemangiomas demonstrate early perfusion with delayed filling. However, this pattern occurs in hepatocellular carcinoma in up to 25% of cases. The sensitivity in the detection of hemangioma varies considerably (65%–90%). This wide range can be attributed primarily to lesion size and location. Lesions 2 cm in diameter or larger can be seen with planar imaging alone in most cases. However, as lesion diameter decreases below 1.5 cm, the visualization of lesions drops considerably, even with single photon emission CT (10). Also, lesions located deep within the liver or adjacent to large blood vessels are less often identified.
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Figure 6. Coronal delayed-phase red blood cell scintigram of the liver shows the two masses (arrows). The photon-deficient regions within the inferior mass correspond to areas of degeneration, which were hypoechoic at US and hypoattenuating at CT.
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MR imaging is very sensitive in the detection of liver hemangiomas. Hemangiomas have very long T2s compared with those of other liver lesions; therefore, hemangiomas retain high signal intensity not only on standard T2-weighted images but also on heavily T2-weighted images. Metastases typically demonstrate signal loss on the latter images. Also, three patterns of enhancement have been identified on dynamic MR images of the liver. Enhancement may be rapid and homogeneous, nodular and discontinuous peripherally with centripetal homogeneous filling, or nodular and discontinuous peripherally with a persistent hypointense center. In one study, washout of contrast material was homogeneous and hemangiomas never became hypointense to the liver during this phase (11). When both T2-weighted and gadolinium-enhanced images were used, the reported sensitivity, specificity, and accuracy in differentiating hemangiomas from neuroendocrine metastases were 98%, 98%, and 99%, respectively (12). In addition, MR imaging is more sensitive than red blood cell scintigraphy in hemangioma detection and is better suited to locating small hemangiomas and those located deep in the liver or adjacent to vascular structures (13).
Follow-up of patients with presumed hemangiomas is not standardized. Some patients are only reevaluated clinically without imaging. In this case, the patient was asymptomatic 3 months after presentation and no further follow-up was planned. Sometimes, repeat US or CT is performed in 3–6 months to verify lesion stability. Finally, confirmatory red blood cell scintigraphy or MR imaging may be performed. The type of follow-up is often predicated on the certainty of the diagnosis.
Because the diagnosis of liver hemangiomas is highly dependent on imaging criteria, it is important to consider this diagnosis in patients with typical or even atypical findings at routine US of the liver. This principle is especially true in patients with a history of malignancy. The choice of confirmatory study—red blood cell scintigraphy or MR imaging—varies among institutions and depends on lesion location, lesion size, and available expertise with different imaging modalities.
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References
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HISTORY
FINDINGS
