Discussion
BGP in WT is referred in literature as Botryoid WT. We preferred the
term Botryoid Growth Pattern to avoid any confusion between gross and
microscopic patterns. BGP in BWT is extremely rare. The two patterns
revealing the disease (abdominal mass and gross hematuria) were
frequently observed in most unilateral BGP cases in
literature4-10. Because the tumor was prone to extend
into the proximal ureter, hydronephrosis was often present on diagnostic
images. The dilation of the three calices may be an important radiologic
feature to preoperatively detect the presence of BGP.
The predisposing syndromes associated with BGP were scarcely described.
Among 77 patients (8 BWT), Vujanić et al reported only one
patient with Denys-Drash syndrome2. In our cases, two
children had a WT1 mutation, in relation with the bilateral disease.
The surgical management of BWT represents a challenge, and discovering a
BGP makes the conservative surgery more complicated, particularly to
remove the whole tumor and the botryoid mass in the pelvis, without any
rupture. In addition, the size of WT was high, rendering the decision of
NSS even more difficult. However, the WT with BGP was located to the
lower pole of the right kidney in all cases and NSS was feasible, with
opening of the renal pelvis and the calyx in order to extract the tumor.
No tumor breach was observed, and 30 to 50% of renal parenchyma was
preserved. The tumor and the BGP were removed en bloc and entirely in
the three cases.
The histological type of WT was stromal or mixed type in our patients
and in both kidneys for each patient, but the BGP itself was an ILNR
every time. In literature, nephrogenic rests were found in 50% of
tumors with BGP2. Yanai et al suggested that
the BGP originated from the ILNR of the pelvis6.
BGP itself did not change the stage or the prognosis of the disease.
Vujanić et al concluded that the intra pelvic botryoid growth
should not be a reason for upstaging a tumor2. Even
when tumor extends into the ureter and reaches the bladder without
infiltrating the wall, it should still be regarded as stage 1 if
completely excised.
The outcome was excellent in patients 1 and 2. They have a moderate
renal insufficiency, with their native kidneys. We only have 9 months
follow-up for patient 3, who has already a renal insufficiency along
with a WT1 mutation.