Cases description
We report our experience of nephron sparing surgery (NSS) in three patients (two boys and a girl) aged 6, 9 and 16 months at diagnosis of BWT and unilateral BGP managed between 1990 and 2020 in our center. Patient’s characteristics are presented in Supplemental Table. The clinical presentation was a gross hematuria (patient 1) and an abdominal mass (patients 2 and 3). A severe hypertension was found in patients 1 and 3. Two children (patient 2 and 3) presented a WT1 predisposition syndrome.
CT scan showed an obstruction of the collecting system with the three calyx dilated in two cases but the BGP was diagnosed on preoperative imaging in only one case (patient 1), with a mass growing into the renal pelvis, while it was discovered during surgery in the other cases (figure 1). The median WT diameter was 11.7 cm.
All three patients had neo-adjuvant chemotherapy according to the SIOP protocols, with Actinomycin D and Vincristine for 3, 4 and 8 weeks, with a very poor response. The date of surgery was brought forward for patients 1 and 2. Doxorubicin, Etoposide and Carboplatin were added in patient 3 but still with little response.
A two-step surgery was performed in all cases, 9 days, 10 days and 1 month apart. The BGP was located on the right kidney for each patient and was easily removed in the three cases, with no adherences to the pelvic wall. The calyx and renal pelvis were opened in all cases in order to remove the tumor and then closed leaving a ureteral catheter and a draining system near the calyx sutures. The BGP was removed along with the whole tumor, with no rupture and no postoperative leak. On the other side, NSS was realized in two patients, and a total nephrectomy was performed in patient 3. The remaining renal parenchyma assessed according to our recent publication3 represented 73/200%, 83/200% and 50/200% respectively in patients 1, 2 and 3. (Figure 2)
The histology of the tumor with BGP was intermediate risk (stromal and mixed type), stage I (patients 2 and 3) and stage II for sinus invasion (patient 1). It was identical in both kidneys for the three patients. The histology of the BGP itself was Intra Lobar Nephrogenic Rest (ILNR) in all cases. Patients received adjuvant chemotherapy according to SIOP protocols for 4 to 8 weeks with no radiation. Patient 1 had an early hepatic relapse (3 months after the end of adjuvant treatment) treated with chemotherapy and tumorectomy of the metastasis.
At a follow-up of 9 months (patient 3), 22 (patient 2) and 23 (patient 1) years, all patients are alive, with a treated hypertension. The Modification of Diet in Renal Disease (MDRD) formula showed a moderate renal insufficiency in the two oldest patients (61ml/mn and 76ml/mn). For the third patient, who is still a toddler, the estimated glomerular filtration rate was slightly decreased (eGFR= 72.9ml/min/1.73m2).