International Journal of Urology (2000) 7, 310–312

Case Report

Renal arteriovenous malformation with thrombus in theinferior vena cava

HIROSHI HARADA,1 MASAKI TOGASHI,2 TAKASHIGE ABE,2

YOSHIHIRO TAKEYAMA,2 TOSHIMORI SEKI2 AND NOBUO OHASHI2

Departments of 1Renal Transplantation and 2Urology, Sapporo City General Hospital, Sapporo, Japan

Abstract Background: Thrombus formation in the inferior vena cava (IVC) is usually seen in cases withmalignancy. In contrast, vascular anomalies hardly ever accompany this disorder. Herein, a case of thrombus formation in the IVC associated with renal arteriovenous malformation (AVM) isreported. Methods/Results: A 50-year-old woman who received transarterial embolization (TAE) for AVMin the right kidney noticed right flank pain with macrohematuria 12 months later. Because radio-graphic evaluation could not rule out malignancy in the kidney, nephrectomy was performed. During nephrectomy, a palpable thrombus was found in the IVC, so thrombectomy was performedsimultaneously. Histopathologic examination revealed an old infarction due to the TAE, circumfer-ential arteriovenous thrombi and a large organized thrombus up to the IVC, but neither renal cellcarcinoma nor transitional carcinoma in the kidney. Conclusions: Careful observation may be required, even after treatment for renal AVM, such asTAE, to avoid the formation of an IVC thrombus.

Key words inferior vena cava thrombus, renal arteriovenous malformation, transarterial embolization.

Introduction

Thrombus formation in the inferior vena cava (IVC) isusually seen in cases with malignancy, dehydration ornephrotic syndrome. In contrast, vascular anomalieshardly ever accompany this disorder. However,Chikaraishi et al. reported idiopathic and sponta-neously regressing thrombus in IVC.1 Its exact mecha-nism remains unclear.

Herein, a rare case of IVC thrombus organized aftertransarterial embolization (TAE) of a renal arterio-venous malformation (AVM) is reported.

Case Report

A 50-year-old woman who had enjoyed good healthpreviously presented with sudden macrohematuria.Excretory urography revealed delineation of the rightnephrogram alone, in spite of excellent visualizationon the pyeloureterogram of the contralateral kidney.Retrograde pyelography showed a few irregular fillingdefects in the right collecting system with markedhydronephrosis and then passage of a clot from theright ureteral orifice was noticed during ureteralcatheterization. An abdominal computed tomography(CT) scan showed clot formation in the right renalpelvis alone. No manifest tumor-like lesion existed.Selective digital subtraction angiography (DSA) of theright renal artery demonstrated the early pooling ofcontrast medium, approximately 1 cm in diameter, withrapid renal vein visualization, in the renal parenchyma(Fig. 1a). These findings suggested AVM causing rightrenal bleeding. Transarterial embolization (5 mL

Correspondence: Dr Hiroshi Harada, Department of RenalTransplantation, Sapporo City General Hospital, Kita 11-jo,Nishi 13-chome, Chuou-ku, Sapporo 060-8604, Japan.Email: oyaji-1@rf6.so-net.ne.jp

Received 25 October 1999; revision 21 February 2000;accepted 21 February 2000.

Renal AVM with IVC thrombus 311

ethanol and a metallic microcoil were used asembolization materials) was successfully used to stopthe macrohematuria. Although the patient had been ingood health after this, right flank pain with macro-

hematuria was noted again 12 months later. At thistime, the physical examination and electrocardiogramwere normal. Results of hematological analysis andchemical analysis of blood were within normal limits.Coagulation tests also revealed no abnormal findings.However, cystoscopy demonstrated bloody urinederived from the right ureteral orifice. An abdominalCT scan disclosed a low-density area around the siteprobably affected by previous TAE. It was mainlyjudged as an infarction, although DSA demonstratedmicroaneurysmal structures around it. Because wecould not completely neglect the coexistence of thesmall foci of hypervascular malignant tumor (Fig. 1b),radical nephrectomy was performed extraperitoneally.During the operation, a palpable thrombus happened tobe found in the IVC, so thrombectomy was performedsimultaneously (Fig. 2). In brief, we first exposed theright renal vein and retracted it. The IVC was con-trolled with a Rummel torniquet at the subhepatic IVCand distal IVC above the bifurcation. After the controlof the contralateral renal vein, the right renal arterywas ligated. An ellipse of the IVC around the rightrenal vein was incised and the thrombus was dissectedcarefully out of the window. Nephrectomy followedthat. Histopathologic examination revealed an oldinfarction due to the TAE, circumferential arterio-venous thrombi and a large organized thrombus up tothe IVC, which was composed of the proliferatingfibroblasts and capillaries with the lymphocytes infil-

Fig. 1 Digital subtraction angiography of the right renalartery. (a) Arteriovenous malformation (AVM; 1 cm indiameter; arrow) in the renal parenchyma, with rapid renalvein visualization. (b) Twelve months after transarterialembolization. Although the nidus-like lesion was not delin-eated, microvessels were found cranially to it. The renalvein and inferior vena cava were visible, even in a artrialphase, and proved the recommunication of AVM.

Fig. 2 A large thrombus was located in the left renalvein up to the inferior vena cava (IVC).

312 H Harada et al.

tration, but neither renal cell carcinoma nor transitionalcell carcinoma existed in the kidney (Fig. 3). The post-operative course was uneventful and the urine was freefrom blood contamination over a follow-up period of 4months.

Discussion

A thrombus in the IVC is usually encountered cases ofmalignant neoplasms, such as kidney cancer, testicular

cancer, multiple myeloma etc. Dehydration, nephroticsyndrome and serious renal infection may also be acommon cause.2–5 Even an idiopathic case has beenreported.1 No report of an IVC thrombus associatedwith AVM, like the present case, could be found in theliterature. It was difficult to judge whether the AVMalone had some role in producing the thrombus orwhether TAE affected it. From the point of view offormation, thrombi are prone to be formed in condi-tions of stagnant blood flow brought about by slowvelocity, hyperviscosity or both.4 In contrast, AVM is a disease characterized by rapid velocity of blood due to the lack of resistance by the capillaries; thus,the quantity of blood passing through the vesselsshould increase. This setting is the hardest environ-ment for thrombus formation. In contrast, the first TAEcould have cut off vessels from all fistulas at the inter-vention, but the gradual recanalization of AVM mayhave resulted in a change of blood flow, causingthrombus formation in incompletely obstructed ves-sels. The recurrence of macrohematuria and radio-graphical recanalization of AVM could be used tointerpret the phenomenon. Histopathologic findingsproved not only thrombosis of the hilar arteries butalso of the veins. In fact, the frequency of this is very low; nevertheless, an idiopathic cause could not begainsaid completely. Thus, long-term and careful fol-low up may be warranted after TAE, even for AVM inthe kidney.

References

1 Chikaraishi T, Kobayashi S, Harada H, Komaki T, Koyanagi T. Idiopathic and spontaneously regressingthrombus in right renal vein and inferior vena cava. Int.J. Urol. 1997; 4: 83–5.

2 Clayman RV, Gonzalez R, Fraley EE. Renal cell cancerinvading the inferior vena cava: Clinical review andanatomical approach. J. Urol. 1980; 123: 157–63.

3 Ivanyi B. Renal complication in multiple myeloma.Acta Morph. Hung. 1989; 37: 235–43.

4 Keating MA, Althausen AF. The clinical spectrum ofrenal vein thrombosis. J. Urol. 1985; 133: 938–45.

5 Mitchell DG, Friedman AC, Druy EM, Swanberg LE,Philips M. Xanthogranulomatous pyelonephritis: Un-usual case of renal vein thrombosis and vena cavalthrombosis. Urol. Radiol. 1985; 7: 35–8.

Fig. 3 (a) Histopathologic specimen of the kidney show-ing organized thrombus of the hilar muscular artery and of the vein (hematoxylin and eosin; H&E). (b)Histopathologic specimen of the inferior vena cavathrombus composed of proliferating fibroblasts and capil-laries with lymphocyte infiltration (H&E).