Applied Radiology

CASE SUMMARY

A 47-year-old male presented to his primary care physician with persistent cough and epigastric discomfort. His chest radiograms showed persistent infiltrates in the left lower lobe over several months. He had been healthy prior to this presentation and had no other complaints. A chest CT was performed to rule out pulmonary neoplasm. In addition to showing left lower lobe pneumonia, several hepatic masses, including a large space-occupying lesion in the left lobe of the liver, were incidentally demonstrated (figure 1). An abdominal MRI scan was performed on the same day to further evaluate the hepatic masses (figures 2, 3).

Diagnosis:

Giant hepatic cavernous hemangioma.

Contrast-enhanced CT demonstrated a large complex soft-tissue mass involving the left lobe of the liver, with peripheral nodular enhancement and a central stellate zone of low density (figure lA). There also are several foci of smaller low density lesions involving the right hepatic lobe; one of these is shown in figure 1B. On MRI scans, there was a large mass (8.0 ¥ 10.5 cm) occupying most of the left lobe of the liver (figure 2A), and three smaller lesions in the right lobe of the liver (figure 2B). The largest lesion demonstrated signal characteristics of giant hemangioma: a large, well defined mass with heterogeneous low signal intensity on T1-weighted images (figure 2) and heterogeneous high signal intensity on T2-weighted images (figure 3). T2 calculations for these lesions range from 104 to 150, consistent with hemangiomas. No additional tests were performed. The patient's left lower lobe pneumonia resolved with a second course of antibiotics, and he remained asymptomatic and healthy.

Discussion:

Giant hepatic cavernous hemangioma (GHCH), defined as a hemangioma in which at least one dimension exceeds 8 cm, is an uncommon benign tumor of the liver.1-3 It rarely coexists with multiple smaller hemangiomas. Scatarige et al2 reported that 1 out of 8 GHCH cases (13%) had coexisting smaller (<5 cm in diameter) hemangiomas. In contrast to smaller incidently discovered hemangiomas, giant hemangiomas are more likely to produce symptoms,3,4 such as right upper quadrant abdominal pain or fullness or upper abdominal mass palpable on physical examination. Therefore, they may often be confused with primary or metastatic malignancy of the liver. The differential diagnosis for GHCH mainly includes hepatic metastases, hepatocellular carcinoma, focal fatty infiltration, hepatic

adenoma, focal nodular hyperplasia, and cholangiocarcinoma. Hemangiomas are difficult to diagnose by means of needle biopsy because of their relatively low cellularity, high vascularity, and fibrous stromal component. Aspirations tend to be extremely bloody, and the cytologic diagnosis of hemangioma often is one of exclusion.5 Therefore, definitive, noninvasive imaging of GHCH is important to make a correct diagnosis and to avoid biopsy and exploratory laparotomy.

Classically, hemangiomas were definitively diagnosed by hepatic angiography, which was the "gold standard" for many years. In the last decade, however, noninvasive imaging modalities have proved just as useful. Currently CT, MRI, scintigraphy with Technetium-99m- labelled red blood cells (Tc-RBC), and occasionally angiography are used to make the diagnosis of hemangioma. Dynamic CT scan is the most commonly used modality to make the initial diagnosis. In most cases, diagnosis of GHCH should be considered when the CT scan shows a large hepatic mass that contains irregular areas of decreased density on the pre-contrast image, peripherally enhancing on bolus dynamic study and exhibiting centripetal but incomplete isodense fill-in on delayed images.1,2,6 Dynamic enhancement patterns are related to the collective size of their constituent vascular spaces, i.e., tumors with slow fill-in have relatively larger spaces and tumors with rapid enhancement have smaller vascular spaces and larger interstitium.7 More recent studies1,2,6,7 reveal that CT features of hemangiomas include a broad spectrum of morphologic patterns, thus raising questions about the specificity of CT diagnosis.9 Hemangiomas examined by CT after slow drip infusion of contrast material may be mistaken for metastases or hepatocellular carcinoma.2,8 CT scans are not sensitive in detecting lesions that measure less than 1 cm in diameter.

Single-photon emission computed tomography (SPECT) Tc-RBC scinitgraphy also is a commonly used modality for diagnosis of hepatic hemangiomas, with specificity approaching 100%. Characteristic findings of hemangioma on Tc-RBC scintigrams include the presence of photopenic defect on early imaging of the tumor, which becomes gradually accumulating and prominently hyperintense relative to the normal liver on 2-hour delayed imaging. Unfortunately, SPECT Tc-RBC is not sensitive in detecting hemangiomas of less than 2 cm in diameter, due to its limited spatial resolution.9,10

MRI is increasingly being used, demonstrating sensitivities which aproach 100% in detection of hemangiomas. An advantage of MRI over CT is its ability to resolve lesions smaller than 1 cm in diameter due to its ability to portray high signal contrast between normal and abnormal tissue for a given site of scanning parameters. On MRI, a moderate sized cavernous hemangioma classically appears as a well defined, smooth-bordered spherical or oval lesion having a homogeneous hypointense-to-isointense signal relative to normal liver on T1-weighted sequences, and a homogeneous hyperintense signal on T2-weighted sequences. However, giant hepatic cavernous hemangioma shows a large, well defined, heterogenous mass containing areas of increased intensity ratio with prologation of TR and TE, cleft-like zones of low signal intensity on T1-weighted images, and higher intensity on T2-weighted images (figures 2,3). Absolute T2 values of tissue have allowed the separation of hemangiomas from malignant tumors.10,11 However, metastatic disease can mimic the long T2 components of the signa and thus, specificity remains to be determined.

Finally, when noninvasive modalities fail to diagnose hemangioma, hepatic angiography should be considered. The typical angiographic feature of hemangioma is a contrast "stain" that arises from the slow flow of the contrast through the large blood pool spaces.

In summary, GHCH is an uncommon benign tumor of the liver and often causes mild symptoms. Biopsy of the tumor is bloody and is generally fruitless, thus it should be avoided. In the present case, multiple hepatic masses were incidentally demonstrated on chest CT. A repeat dynamic CT scan would not give definite diagnosis because of multiple lesions with variable sizes. Because SPECT Tc-RBC has limited sensitivity in detecting those small lesions, and because the patient's unremarkable past medical history makes such large hepatic metastases unlikely, we chose MRI as the diagnostic tool.

References

1. Choi BI, Han MC, Park JH, et al: Giant cavernous hemangioma of the liver: CT and MR imaging in 10 cases. AJR 152:1221-1226, 1989.

2. Scatarige JC, Kenny JM, Fishman EK, et al: CT of giant cavernous hemangioma. AJR 149:83-85, 1987.

3. Cronan JJ, Esparza AR, Dorfman GS, et al: Cavernous hemangiomas of the liver: Role of percutaneous biopsy. Radiology 166:135-138, 1988.

4. Ishak KG, Robin L: Benign tumors of the liver. Med Clin North Am 59:995-1013, 1975.

5 Dodd LG, Mooney EE, Layfield LJ, et al: Fine-needle aspiration of the liver and pancreas: A cytology primer for radiologists. Radiology 203:1-9, 1997.

6. Freeny PC, Marks WM: Patterns of contrast enhancement of benign and malignant hepatic neoplasms during bolus dynamic and delayed CT. Radiology 160:613-618, 1986.

7. Yamashita Y, Ogata I, Urata J, et al: Cavernous hemangioma of the liver: Pathologic correlation with dynamic CT findings. Radiology 203: 121-125, 1997.

8. Itai Y, Ohtomo K, Araki T, et al: Computed tomography of cavernous hemangioma of liver. Radiology 137:149-155, 1980.

9. Krause T, Hausenstein K, Studier-Fisher B, et al: Improved evaluation of technitium-99m-red blood cell SPECT in hemangioma of the liver. J Nucl Med 34:375, 1993.

10. Beers BV, Demeure R, Pringot J, et al: Dynamic spin-echo imaging with Gd-DTPA: Value in the differentiation of hepatic tumors. AJR 154: 515-519, 1990.

11. Brae RL, Schwab RE, Glazer GM, et al: The varied appearances of hepatic cavernous hemangiomas with sonography, computed tomography, magnetic resonance imaging and scintigraphy. Radiographics 7:1153-1175, 1987.

Prepared by Tom X.L. Tan, MD, William F. Bennett, MD, and Charles F. Mueller, MD, Ohio State University Medical Center, Columbus, OH.

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