Case Study of the Month

A Case of Renal Capsular Liposarcoma with Intracaval Fat

Thrombus

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Giuseppe Ciccarello a, Giuseppe Mucciardi a, Giuseppe Morgia a, Francesco Spinelli b,Giorgio Ascenti c, Luciano Macchione a, Carlo Magno a,*

a Department of Urology, University of Messina, Messina, Italyb Department of Vascular Surgery, University of Messina, Messina, Italyc Department of Radiology, University of Messina, Messina, Italy

Article info

Article history:Accepted July 15, 2009Published online ahead ofprint on July 28, 2009

Keywords:

Liposarcoma

Intracaval thrombus

Surgical therapy

Abstract

A 58-yr-old woman was referred to our hospital for hematuria and a painless,

rapidly growing abdominal mass. Computed tomography showed a rounded mass,

23 � 19 cm in diameter, spread over the left retroperitoneal space. A thrombus was

observed occupying the left renal vein until the vena cava. Total left nephrectomy

with excision of the retroperitoneal mass was carried out. A cavotomy highlighted

the intraluminal thrombus, which was easily detached with a forced Valsalva

maneuver. The pathologic examination demonstrated a well-differentiated lipo-

sarcoma of the renal capsule with fat thrombus in the vena cava. At 24 mo follow-

up, there was no evidence of recurrence.

# European Association of Urology Published by Elsevier B.V. All rights reserved.

* Corresponding author. University of Messina, Via Garibaldi 118, 98122 Messina, Italy.E-mail address: cmagno@unime.it (C. Magno).

1. Case report

A 58-yr-old woman was referred to our hospital for

hematuria and a rapidly growing abdominal mass. The

patient had undergone radical hysterectomy for uterine

fibroma 13 yr earlier. She had no history of urologic disease,

and blood tests showed normal results.

Physical examination showed a painless mass spread

over the left half of the abdomen (Fig. 1). An abdominal

ultrasound examination revealed a voluminous, hetero-

geneous, well-defined mass extending from the lower pole

of the left kidney to the pelvis, with anechoic and

hyperechoic images inside. Computed tomography

(CT) was performed and showed a rounded mass,

23 � 19 cm in diameter, spread over the left retroperitoneal

space, dislocating adjacent abdominal organs. The mass

0302-2838/$ – see back matter # European Association of Urology Published

apparently arose from the left renal capsule and was

characterized by a fatty mass with internal areas of fluid.

The angiography showed a double left renal artery (Fig. 2).

The left renal vein ran between the renal arteries and

showed intravascular focal filling defects until the vena

cava, which was detected as thrombus by ultrasonography

performed with a contrast agent for ultrasound imaging

(SonoVue, Bracco SpA, Milan, Italy; Fig. 3).

We carried out a total left nephrectomy with excision of

the retroperitoneal mass (Fig. 4). A cavotomy was per-

formed starting from the outlet of the left renal vein, and it

highlighted a thrombus that was easily detached with a

forced Valsalva maneuver caused by the anesthesiologist.

The pathologic examination showed well-differentiated

liposarcoma of the renal capsule. The tumor infiltrated the

superior pole of the left kidney (Fig. 5). At 24-mo follow-up,

by Elsevier B.V. All rights reserved. doi:10.1016/j.eururo.2009.07.021

Fig. 1 – Preoperative picture showing the abdominal mass.

Fig. 2 – Preoperative computed tomography scan (a,b) showing the presence of(c) showing a double left renal artery.

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the patient remained asymptomatic, without evidence of

recurrence on control with CT scan.

2. Discussion

Sarcomas of the genitourinary (GU) tract are most

commonly reported to be leiomyosarcomas (47% renal,

50% bladder, 57% prostate, and 19% paratesticular sarco-

mas), followed by liposarcomas [1,2]. Liposarcoma accounts

for at least 20% of all soft-tissue sarcoma in adults, with a

peak incidence between 50 and 65 yr of age and a male

predominance. It may occur anywhere in the body,

although the most common sites are the thigh and the

retroperitoneum [3]. It could be difficult to establish the

exact origin of a tumor that usually derives from fat, from

a mass origining from the inferior pole of the left kidney and angiography

Fig. 3 – Preoperative ultrasonography performed with contrast agent forultrasound imaging (Sonovue) showing an intracaval thrombus.

Fig. 5 – The mass with (a) the kidney and (b) the thrombus.

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sinus, or from the renal parenchyma [4]. Primary tumors of

the renal capsule are uncommon, and liposarcoma of the

renal capsule is distinctly rare. There have been only 18

reports of liposarcoma arising from the renal capsule [5–7],

and to the best of our knowledge, this is the first case of a

concomitant fat thrombus in the vena cava that was well

Fig. 4 – Intraoperative picture showing (a) the mass and (b) the intracavalfat thrombus.

identified with the use of an ultrasonographic contrast

agent and was easily removed through a minimum

cavotomy with a forced Valsalva maneuver caused by the

anesthesiologist.

Liposarcomas are classified into five histologic subtypes:

well differentiated, dedifferentiated, myxoid, round cell,

and pleomorphic [8]. The well-differentiated liposarcoma is

a locally aggressive, nonmetastasizing, highly locally

recurrent, malignant mesenchymal neoplasm composed

of a mature adipocytic proliferation with significant

variation in cell size and focal nuclear atypia. A well-

differentiated liposarcoma usually presents as a deep-

seated, painless, enlarging mass that can slowly grow for a

long time to attain a very large size. Well-differentiated

liposarcomas can be subdivided morphologically into four

main subtypes: adipocytic (lipoma-like), sclerosing, inflam-

matory, and spindle cell [3]. Histologic grade, reflecting the

extent of differentiation, remains the most important

prognostic factor [8]. Common sites of metastases of renal

sarcoma are the lung, the lymph nodes, and the liver [9].

The renal adipocytic liposarcoma has no metastatic

potential unless it faces dedifferentiation; when it does, it

may more correctly be named atypical lipoma or atypical

lipomatous tumor [4].

Liposarcomas are often considered difficult to distin-

guish from angiomyolipomas (AMLs) because both are large

fat-containing lesions [9]. Because prognosis and often

treatment differ for these two conditions, it is important to

have an accurate diagnosis before any treatment or

management is instituted. Three major imaging findings

(defect in the renal parenchyma, vessels in the lesion,

presence of additional AMLs) are crucial for making the

distinction [10]. Evidence suggests that complete surgical

resection with a negative margin can offer the best chance

of cure in patients who present with primary disease.

The relatively poor prognosis of GU soft-tissue sarcomas

may be explained by the higher proportion of high-grade

B. A differential diagnosis between angiomyolipomas

and liposarcomas is not able to be performed with

imaging studies.

C. It is important because treatment and prognosis are

different.

D. Angiomyolipomas and liposarcomas do not have

similar characteristics.

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tumors, the proportion of patients who present with

metastatic disease, the larger tumor size, and the anatomic

site [1].Cancer-related survival in patients with GU sarcoma

is more unfavorable than in patients with sarcoma at

all sites and is reported to be 56% at 5 yr. The prognosis of

renal sarcoma is especially poor, with a reported 5-yr

survival rate of 29% [1,9].

Primary surgical resection is the main treatment. The

most important prognostic factors for survival are histologic

subtype or grade and completeness of resection [8], as

occurred in our case, despite the presence of a wide

intracaval vein thrombus that was easily removed without

complications.

In conclusion, after an accurate literature review, we can

assert that the case presented is the first of a kidney

liposarcoma associated with a fat intracaval thrombus that,

after radical removal, does not seem to influence prognosis

after 24 mo of follow-up.

Conflicts of interest: The authors have nothing to disclose.

EU-ACME question

Please visit www.eu-acme.org/europeanurology to

answer the following EU-ACME question online (the

EU-ACME credits will be attributed automatically).

Question:

Is a differential diagnosis between angiomyolipomas and

liposarcomas important?

A. It is not important distinguish angiomyolipomas and

liposarcomas because treatment and prognosis is the

same for both.

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