Case 1097_03 --Embolization of angiomyolipomas

Case Reference No. CC-1097-03

The patient is a 67-year-old woman with tuberous sclerosis and right flank pain. MR imaging demonstrated bilateral nephromegaly with approximately 80% of the volume of both kidneys replaced by multiple bilateral angiomyolipomas (AMLs). In addition, there was a subacute hematoma involving the lower pole of the right kidney, presumably from an angiomyolipoma that had bled (Fig. 1). A large feeding artery to the hematoma was identified on the MR study (not shown).

A selective right renal arteriogram obtained with use of a Simmons catheter demonstrated a markedly enlarged and deformed kidney with multiple diffuse AMLs. The two largest lesions were within the upper pole and the interpolar region. In addition, there were multiple dilated venous spaces, most marked in the upper pole of the right kidney, in keeping with the early draining vein of an arteriovenous (AV) fistula. The decision was made to selectively embolize the larger upper pole lesion. Three- and 5-mm coils were deployed within the appropriate subselected branch of the right upper pole renal artery. After the procedure, there was minimal filling of the venous spaces within the upper pole, with marked venous stasis.

Two days later, further diagnostic arteriography was performed (Figs. 2, 3). In this patient, a dilemma arose from the extensive involvement of the right kidney with AML lesions. It was very difficult to distinguish AML tumor from normal underlying renal parenchyma. After having embolized the upper pole arterial supply, embolization of the large lower mass, which was presumed to have bled based on the MR study, would have entailed embolization of most of the remaining renal parenchyma. It was decided to treat the AV fistula alone and not the entire mass. Initially, large polyvinyl alcohol particles were injected into the artery and were noted to rapidly flow through the AV fistula. A single 3-mm x 30-mm coil was deployed into its feeding artery. A repeat arteriogram demonstrated good results with complete embolization of the AV fistula (Fig. 4).

The selective left renal arteriogram demonstrated diffuse AML tumor involvement but did not demonstrate a dominant lesion. The left kidney was therefore not treated.

Although AMLs are benign lesions, large and/or symptomatic lesions are frequently excised or treated because of the risk of spontaneous hemorrhage. Typically, lesions larger than 4 cm are sent for prophylactic embolization. However, the literature on the prophylactic treatment of these highly vascular tumors is relatively limited. While most physicians agree that prophylactic treatment of AMLs is beneficial in limiting the sometimes life-threatening complications of spontaneous bleeding, the size of tumors to be treated, and well as the treatment of the lesions (embolectomy versus surgery) remains controversial. At our institution, the decision to treat lesions larger than 4 cm is based upon a review of 5 cases and 21 reported cases from the literature, a relatively small population.

Fig. 1. Axial FMP SPGR/90 MR examination of the kidneys. Both kidneys are enlarged, with replacement of nearly all the renal parenchyma with AML tumor (asterisk). Note the hematoma involving the lower pole of the right kidney.

Fig. 2. Large lower pole AML involving the majority of the remaining kidney. Multiple aneurysmally dilated vessels to the lower pole are shown. An AV fistula involving the previously embolized upper pole AML is also now visualized (arrows).

Fig. 3. Selective injection shows the dilated vessels and pseudoaneurysms.

Fig. 4. Selective right renal arteriogram after embolization of the upper pole AV fistula.

Questions

1) How would you have treated this patient?

2. Should we have ignored the nonbleeding upper pole lesion, and embolized the entire lower pole, which contained the AML which was known to have bled?

3. Was it necessary to treat the AV fistula?

4. Would you have used different embolization agents?

5. Should we have treated the left kidney prophylactically?

6. When is prophylactic embolization of AMLs necessary?

7. Since AV fistulas are not commonly associated with AMLs, would you entertain an additional/alternative diagnosis such as renal cell carcinoma?

References

Chatterjee T, et. al. Recurrent bleeding of angiomyolipomas in tuberous sclerosis. Urologia Internationalis 1996; 56:4447.

Corr P, Yang WT, Tan I. Spontaneous hemorrhage from renal angiomyolipomas, Australasian Radiol 1994; 38:132134.

Hamlin JA, et. al., renal angiomyolipomas: long-term follow-up of embolization for acute hemorrhage. Can Ass Rad J 1997; 48:191198.

Han YM, et al. Renal angiomyolipoma: selective arterial embolization-effectiveness and changes in angiomyogenic components in long-term follow-up. Radiology 1997; 204:6570.

Kennelly MJ, et. al. Outcome analysis of 42 cases of renal angiomyolipoma. J Urol 1994; 152:188191.

Koike H, et al. Management of renal angiomyolipoma: a report of 14 cases and review of the literature. Is nonsurgical treatment adequate for this tumor? Eur Urol 1994; 25:183188.

Soulen MC, et al. Elective embolization for prevention of hemorrhage from renal angiomyolipomas. J Vasc Interv Radiol 1994; 5:587591.