CASE REPORT

A trio of
multiple \Nilms'

tumours

s. Andronikou
FC Rad Diag (SA)

C. Weiman
MBChB

E. Kader
MBChB

Department of Paediatric Radiology, University
of Cape Town and Institute of Child Health, Red

Cross War Memorial Children s Hospital,
Rondebosch, Cape Town

Corresponding author
S. Andronlkou

Department of Paediatric Radiology
Red Cross War Memorial Children's Hospital

CapeTown
7700

Telephone: 021-6585442
Fax: 021-6585101

E-mail: docsav@mweb.co.za

Abstract
Wilms' tumour is the
commonest mal ignant
abdominal tumour in
children. Unilateral
mu Iticentric, and
bilateral Wilms'
tumours are, however,
lesscommon,
occu rri ng in 7<Yo and
5% of cases
respectively. These are
often associated with
sporadic aniridia,
genitourinary
anomalies,
hem ihypertrophy and
nephroblastomatosis.
Nephroblastomatosis
is a separate entity that
may act as a precursor
of Wilms' tumours. We
present th ree cases of
multiple Wilms'
tumours. Two cases
also had
nephroblastomatosis
which was not seen on
pre-operative CT
imagi ng but was
identified in one case

4 SAJOURNAL OF RADIOLOGY. August 2000

at MRI. In cases of
multiple Wilms'
tumours, MRI provides
better delineation of
the tumours and may,
therefore, affect
management.
Key words
Wilms' tumour,
nephroblastomatosis,
magnetic resonance
imaging (MR!),
computed tornogrephy
(CT), horseshoe kidney.

Introduction
Wilms' tumour (WT) is the com-

monest malignant abdominal tumour
in children.' Unilateral multicentric,
and bilateral WT are less common. We
present three cases of multiple WT
and their imaging features.

Case 1
A 2-year-01d boy presented with

a month's history of weight loss and a
palpable right-sided abdominal mass.
Ultrasound (US) and computed tom-
ography (CT) showed large upper
pole and smaller lower pole masses
in the right kidney (Figures 1a and b).
A right nephrectomy was performed
and histology demonstrated nephro-
b1astomatosis and three WT of favour-
able histology.

Case 2
A 4-year-old boy with multiple

congenital anomalies, including a
horseshoe kidney, presented with
macroscopic haematuria. A palpable
abdominal mass was sonographically
shown to arise from the left side of
the horseshoe kidney. On CT, bilat-
eral renal masses were seen in keep-
ing with WT (Figures Za and b). In

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A trio of multiple Vvi lrns+u.rrncnrrs

from page 4

Figures la and b: Two tumours in a single kidney
Case 3

A 4-year-
old boy pre-
sented with a
lO-day his-
tory of ano-
rexia, ab-
dominal pain
and intermit-
tent fever.An
US and CT
scan (Figure
3a) demon-
strated bilat-

b. A lowe~ CT slice demonstrates the enhancing midline isthmus
(arrow) br/dglng the tumour masses.

a, Post-contrast CT shows a low den~ity mass (arrow) in the posterola-
teral upper pole of the fight kidney with a typical claw sign (arrowheads).

eral renal masses (two
in the right kidney and
one on the left), After
chemotherapy, the left
WT was removed by
partial nephrectomy. A
DMSA scan demon-
strated a differential
function of 68% on the
right and 32% on the
left, Repeat CT
showed more than one
mass in the right kid-
ney, In view of possible

view of the clinical setting, the child salvage surgery in the
was managed conservatively until his better functioning right kidney, an
death, MRI was performed to delineate the

Figures 211 and b: Bilateral tumours in a horseshoe kidney extent of the masses,
At least five masses
were demonstrated
(Figures 3b,c,d), three
of which were
histologically proven
nephroblastomatosis,
A repeat course of
chemotherapy was in-
stituted,

mour of children between one and
eight years of age and is the third com-
monest cause for a renal mass in child-
hood after hydronephrosis and
multicystic dysplastic kidney.' The
commonest presentation is with an
asymptomatic abdominal mass. Un-
common presentations include ab-
dominal pain, fever, anorexia, haema-
turia and hypertension, Although
mostly sporadic, WT are associated
with several conditions, including
horseshoe kidneys, Beckwith-
Wiedemann syndrome and sporadic
aniridia.? Bilateral tumours occur in
5% of cases and unilateral multicen-
tric tumours in 7%. Bilateral tumours
are often associated with sporadic
aniridia, genitourinary anomalies,
hemihypertrophy and nephro-
blastoma to sis (persistent metanephric
blastemal rests found after 34 weeks'
gestation). Nephroblastomatosis is
considered an intermediate between
a malformation and neoplasrn.ê'
These nephrogenic rests are seen in
1% of autopsies of children under
three months of age.' They are asso-
ciated with synchronous bilateral WT
in 99%, and with metachronous bi-
lateral WT in 94% of cases,
Nephroblastomatosis therefore has

to page 7

b. Post-contrast CT,of tlJe same patient shows another mass with
cystic components In the anteromediallower pole of the right kidney,

Discussion
Wilms' tumour is

the commonest malig-
nant abdominal tu-

a, Post~contrast CT shows masses in both kidneys with a contrast-
enhancing isthmus (arrow) of the horseshoe kidney.

SAJOURNAL OF RADIOLOGY. August 20006



A trio of multiple Wilms'turllours

frompage6

a. Post-contrast CT shows bilateral low density renal masses
with cystic components. Note the thrombus in the IVC (arrow).

e. Axial T2-weighted MRI shows clear differentiation between the
inhomogeneous Wilms' mass (arrow) with increased central T2 signal
intensity, and the peripheral, flatter nodules of nephroblastomatosis
(arrowhead) that are iso-intense to cortex.

malignant potential and is hence a
precursor of WT.3 While ultrasound
is often the initial investigation and
provides good detail of IVC tumour
thrombus, CT scanning provides bet-
ter detail of the tumours. Post-treat-
ment imaging is necessary to detect
recurrence and metachronous tu-
mours - especially with associations
known to develop multiple WT.2 On
CT, the tumour is typically of inho-
mogeneous low-density with in-
creased inhomogeneity post-contrast.
A 'claw sign' confirms the renal ori-
gin of the mass. The mass is usually
solid but haemorrhage and necrosis
may cause cystic areas. Calcification

b. Axial T2-weighted MRI post left partial nephrectomy shows an
anteromedial upper pole renal mass (arrowheads) that is iso-intense
to the rest of the kidney.

d. T2-weighted MRlln the coronal plane al/ows evalualion
of multiple masses (open arrows) with greater ease.

is seen in up to ] 5% of cases. MR! is
helpful in difficult cases as coronal
imaging allows better tumour deline-
ation. Generally WT are heterogene-
ous with low signal intensity on Tl-
weighting, high signal on T2-weight-
ing and show inhomogeneous contrast
enhancement. Haemorrhage and
necrosis may alter these appearances.'
Differential diagnosis includes neu-
roblastoma, nephroblastcmatosis,
mesoblastic nephroma, multilocular
cystic renal tumours, renal cell carci-
noma, renal lymphoma, renal leukae-
mia, clear-cell sarcoma and rhabdoid
tumours of the kidney. Nephrogenic
rests may either be perilobar (periph-

7 SAJOURNAL OF RADIOLOGY. August 2000

eral) or intralobar (central). The in-
tralobar rests are associated with more
frequent development ofWT and at
a younger age.' On CT, the nephro-
genic rests are typically well-defined
plaque-like or nodular subcapsular
masses that are homogenously iso-
dense to renal cortex. They enhance
poorly and hence appear hypo-dense
relative to renal cortex. On MR! they
are iso- to hypo-intense to renal cor-
tex on both Tl- and T2-weighted se-
quences. They enhance poorly with
gadolinium and are hypo-intense rela-
tive to renal cortex. Both
nephroblastomatosis and WT are best
seen on post-gadolinium images. The

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A trio of rriu lt.ipf e Wilms'tumours

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most reliable differentiation between
them is based on their homogeneity?
In practice, the imaging" and surgery'
for wr often differs from the National
Wilms' Tumour Study Group
(NwrSG) protocol. Controversial
points include radiological or surgical
staging, timing of chemotherapy, the
adequacy of partial nephrectomy, and
the optimum follow-up surveil-
lance.v' This is especially so for mul-
tiple wr where the surgical approach
and need for accurate follow-up sur-
veillance is complicated by the pres-
ence of multiple potentially malignant
nephrogenic rests. Cases one and three
had nephroblastomatosis which was
not seen on pre-operative CT imaging,
In case three it was, however, identi-
fied on the pre-operative MRI scan,
In view of these problems, it may be
advisable to consider MRI in compli-
cated cases with multiple wr.

Conclusion
In cases of multiple wr, MRI pro-

vides better delineation of the tu-
mours and increased sensitivity for
detecting nephroblastomatosis. It
should be considered in the tumour
work-up as it may affect management.

References
1. Chapman S, Nakielny R. Aids to radiological

differential diagnosis. 3rd ed. London: WB
Sanders. 1995:309·310, 317.

2. Barnewolt CE, Paltiel HJ, Lebowitz RL,
Kirks DR. Genitourinary tract. fn: Kirks DR
& Griscom NT, eds. Practical paediatric
imaging. 3rd ed. Philadelphia: Lippincott-
Raven. 1998:1111·1126.

3. Rohrschneider WK, Weirich A, Rieden K,
Darge K, Trëger J, Graf N. US, CT and MR
imaging characteristics of ne p hr o-
blastomatosis. Paediatr Radial, 1998;
28:435·443.

4. Goske MJ, Mitchell C, Reslan WA. Imaging
of patients with Wilms' tumour. Sem Ural
Onco11999; 17:11·20.

5. Ross JH, Kay R. Surgical considerations for
patients with Wilms' tumour. Sem Ural
Onco11999; 17:33·39.

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