Japanese Journal of Clinical Oncology 33:44-46 (2003)
© 2003 Foundation for Promotion of Cancer Research
Neovasculature of Benign Thrombus of the Inferior Vena Cava Demonstrated by Computed Tomography during Hepatic Arteriography, Mimicking a Small Hepatocellular Carcinoma
Departments of 1 Diagnostic Radiology and 2 Hepatobiliary Surgery, National Cancer Center Hospital, Tokyo, Japan
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONCASE REPORTDISCUSSIONREFERENCES |
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A 64-year-old man who underwent hepatectomy for hepatocellular carcinoma (HCC) 4 years ago followed by transarterial chemoembolization for recurrent foci 1 year later had a thrombus in the inferior vena cava (IVC). Tumor thrombus derived from HCC was suspected owing to the increase in size and hepatic arteriography was performed. Common hepatic arteriography demonstrated a small stain suggesting a recurrent HCC in the remnant liver. However, CT during hepatic arteriography revealed that the stain localized not in the liver but within the thrombus in the IVC; there was no recurrent HCC in the liver. The dense stain associated with thin neovasculature developed through the thrombus was recognized. The thrombus spontaneously regressed 8 months later. It was speculated that the neovasculature played an important role in a process of absorption of the thrombus. One should note that the stain shown on angiography does not always suggest that the lesion is localized in the liver and is malignant.
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONCASE REPORTDISCUSSIONREFERENCES |
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A thrombus in the inferior vena cava (IVC) is usually benign and is readily demonstrated by ultrasonography, computed tomography (CT) and magnetic resonance (MR) imaging, whereas malignant thrombus or tumor thrombus is associated with a malignant neoplasm such as hepatocellular carcinoma (HCC) (1,2), renal cell carcinoma and other rare intraluminal sarcomas of the IVC (3); they frequently have neovasculature within it. We have encountered a non-malignant thrombus in the IVC in association with neovasculature, which mimicked a small HCC.
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CASE REPORT |
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TOPABSTRACTINTRODUCTIONCASE REPORTDISCUSSIONREFERENCES |
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A 64-year-old man underwent wedge resection for HCC 4 years ago and transarterial chemoembolization for recurrent HCC measuring 1.8 cm, in segment 6, 1 year later. Follow-up dynamic CT performed every 4 months revealed no recurrent foci of HCC but a thrombus of the IVC measuring 4 cm in length. It was not enhanced by contrast medium. MR imaging failed to demonstrate HCC lesion and revealed a thrombus within the IVC whose intensity was as high as the bone marrow of the vertebral bone on T1 weighted image (T1WI) and was a mixture of hyper- and hypo-intensity on T2WI. The thrombus was not enhanced by Gd–DTPA. During a 2.5 year follow-up, the thrombus gradually increased in size to 7 cm in spite of normal values of
-fetoprotein and des-
-carboxyprothrombin. Two months later, hepatic angiography followed by CT during hepatic arteriography was performed for further examination. The common hepatic arteriography demonstrated a small stain measuring 1 cm in diameter, which suggested recurrent HCC that might have developed in the caudate lobe (Fig. 1A). CT during common hepatic arteriography was carried out after transportation of the patient from the angiography room to the CT suite. CT started 5.5 s after the beginning of injection of 30 ml of 100 mg I/ml of ioversol (300 mg I/ml, Optiray; Yamanouchi) diluted with saline solution (1:2) at a rate of 2 ml/s (4). A small stain located just lateral to the thrombus in the IVC was demonstrated (Fig. 1B). The stain was shown to be fed by the posterior segmental branch of the right hepatic artery rather than the caudate one. Thin arteries were recognized to traverse the thrombus in the axial slice (Fig. 1B) and more cranial slices (Fig. 1C). Subsequently, inferior vena cavography followed by CT during the inferior vena cavography (Fig. 1D) was carried out. It showed more clearly the thrombus attached to the posterior wall of the IVC. The small stain was presumed to be neovasculature which developed within the mural thrombus because of absence of recurrent HCC around there.
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Follow-up dynamic CT performed 8 months later demonstrated a faint arterial branch corresponding to the dense stain seen on the previous CT during common hepatic arteriography in the early phase (Fig. 1E) and a spontaneously reduced thrombus in the IVC in the late phase (Fig. 1F). Even though the thrombus repeated its increase and decrease in size, no intrahepatic recurrent HCC was recognized over a period of more than 3 years.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONCASE REPORTDISCUSSIONREFERENCES |
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The combination study of CT and hepatic arteriography was useful for identifying the location of the neovasculature, whether within or outside the IVC, because it was presumed to be intrahepatic recurrent HCC on arteriography alone. It also demonstrates thin arterial branches traversing and coursing cranially in the thrombus of the IVC. This neovasculature was speculated to play an important role in recanalizing within the thrombus and absorbing it; in fact, it was spontaneously reduced during the 8 month follow-up period. CT during hepatic arteriography suggested that the neovasculature was mainly supplied from the feeding artery which nourished the wall of the IVC, namely the posterior segmental branch of the right hepatic artery.
It is commonly observed that benign thrombi develop in the auricle of the left atrium (5) or the aortic aneurysm (6) and rarely in the old hematoma in the hepatic cyst (7). However, benign thrombi associated with neovasculature in the IVC have not been reported, to our knowledge.
The stain demonstrated on CT during common hepatic arteriography seems to be slightly dense like an aneurysm. It could be speculated to be caused predominantly by the injected dose of contrast medium to the right hepatic artery due to the dislocation of the catheter tip from the common hepatic artery during the transportation of the patient. No finding of an aneurysm-like structure was recognized on either dynamic CT or MR imaging.
To differentiate benign from malignant thrombus, the following findings could be noted: the stain was located in the peripheral portion of the thrombus rather than the central one, which is unusual in HCC and renal cell carcinoma where a lot of thin neovasculature is seen in the whole thrombus such as threads and a streaked appearance (1,2). The absence of a primary lesion of HCC indicates that the thrombus is benign, even though a very unusual case has been reported in which the portal tumor thrombus was the only primary site of HCC (8).
Color Doppler ultrasonography has been reported to be helpful in distinguishing malignant and benign thrombus in the portal vein; in the former, pulsatile arterial flow is recognized with a high sensitivity of more than 90% and a specificity of 100% (9,10). Therefore, it is of interest whether the neovasculature within the benign thrombus could be demonstrated or not by color Doppler sonography, although this was not applied in our case, unfortunately.
One should note that the neovasculature which develops within the thrombi does not always suggest malignant nature.
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FOOTNOTES |
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* Present address: Third Department of Surgery, Nihon University School of Medicine, Nihon, Japan.
+ For reprints and all correspondence: Kenichi Takayasu, Department of Diagnostic Radiology, National Cancer Center Hospital, 5–1–1, Tsukiji, Chuo-ku, Tokyo 104-0045, Japan. E-mail: ktakayas@ncc.go.jp
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REFERENCES |
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Received August 16, 2002; accepted October 7, 2002
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