Abstract
Abstract
Background:
Cystic nephroma (CN) is a rare benign renal neoplasm. The differential diagnosis of cystic partially differentiated nephroblastoma is only possible with pathological findings. Therefore, surgical resection is necessary to diagnose suspected CN lesions. Because CN is usually well demarcated and has a good prognosis, partial nephrectomy is recommended for its treatment. However, to our knowledge, laparoscopic treatment of CN has not been reported. We describe 2 cases of large CNs successfully treated: Case 1 was a 9-month-old boy with a lower polar mass in the right kidney, which occupied two-thirds of the kidney, and Case 2 was a 9-month-old boy with an upper polar mass in the left kidney, which occupied three-fourths of the kidney.
Materials and Methods:
Using the transperitoneal approach, the lesion was detected by a laparoscopic ultrasound probe, and vessels in the affected region were dissected. After the renal artery was clamped with bulldog clips, the parenchyma of the affected region was divided with an ultrasonically activated scalpel. The partly cut pelvis was closed by suturing, and the resected stump was coated with hemostatic agents and covered with the pediculate peritoneum.
Results:
The lesion was not exposed during surgery, and the microscopic features were consistent with CN in both cases. Residual renal function was good, and no residual tumor was found in both cases for over a year.
Conclusions:
Laparoscopic partial nephrectomy is a feasible approach to treat large CNs. When it is difficult to close the resection stump by parenchymal suturing, covering the stump with hemostatic agents and pediculate peritoneum is feasible.
Introduction
C
Materials and Methods
Case 1
A 9-month-old boy was referred to our department because of a lower polar multilocular cystic mass of the right kidney. The lesion was incidentally detected by abdominal ultrasound during the follow-up for a slight ureteropelvic junction stenosis of the left kidney. Computed tomography (CT) showed a well-circumscribed mass (4.3×3.7×3.8 cm), which occupied two-thirds of the right kidney (Fig. 1a and b).
Case 2
A 9-month-old boy was referred to our department for intussusception, and a left upper polar renal multilocular cystic mass was incidentally detected by abdominal ultrasound. High-pressure enema was unsuccessful, and the intussusception was reduced laparoscopically with three 5-mm ports. The renal mass was further examined after the operation, and CT revealed a well-circumscribed mass (5.2×4.3×3.5 cm), occupying three-fourths of the left kidney (Fig. 1c and d). The patient also had hypertension with systolic blood pressure of 140 mm Hg, which needed medication.
In both cases, CN or CPDN was suspected, but differential diagnosis was not possible without surgical resection. Single and/or multiple branches of the artery and vein to the intact renal regions were present in both cases; therefore, laparoscopic partial nephrectomy was performed. The age at operation was 11 months for Case 1 and 10 months for Case 2.
Surgical technique
First, a ureteral catheter was inserted in the pelvis of the affected kidney under cystoscopic guidance. The child was positioned in a semilateral position, and a 12-mm trocar was inserted at the umbilicus using the open technique. After carbon dioxide pneumoperitoneum was established at 10 mm Hg, a 5-mm port was inserted under direct vision at each of the following three locations: the affected side hypogastrium, the opposite side flank, and the epigastrium. The colon was dissected away from the affected kidney, and the affected side ureter was identified at the lower pole of the kidney. The lesion was then detected with a laparoscopic linear ultrasound probe, UST-5550 (Aloka, Tokyo, Japan) and the affected part was dissected from the surrounding tissue.
Next, the arteries and veins of the affected region were identified, dissected, and excised using Hem-o-Lok® clips (Teleflex Medical, Durham, NC) and a vessel-sealing device, BiCision® (ERBE, Tübingen, Germany) (Fig. 2a and b). The lesion's boundaries were marked using a laparoscopic linear ultrasound probe, UST-5550. The renal artery of the affected side was clamped with Laparoscopic bulldog clips® (Aesculap, Tuttlingen, Germany), and the parenchyma of the affected region was dissected and divided with a Harmonic® scalpel (Ethicon, Cincinnati, OH). Bleeding from the resected stump was stopped by suturing with monofilaments; the Laparoscopic bulldog clips® were released after hemostasis was confirmed. The pelvis was partially cut on the affected side, divided with Endo Shears™ (Covidien, Mansfield, MA), and then closed with 5-0 monofilament sutures (Fig. 2c). Closure and the absence of leakage were confirmed by injecting dye through the ureteral catheter. The remaining kidney was approximately one-third and one-fourth of its original size for Cases 1 and 2, respectively. The resected stump was covered with Beriplast® P (CSL Behring, King of Prussia, PA), Surgicel® (Ethicon, Somerville, NJ),8,9 and finally pediculate peritoneum to maintain hemostasis and fix the position of the remaining kidney (Fig. 3). The resected part was removed by a hypogastric incision and placed in a collecting bag.
Results
The operative times were 460 minutes (Case 1) and 415 minutes (Case 2), and the total warm ischemia times were 63 minutes (Case 1) and 28 minutes (Case 2). The amount of intraoperative bleeding was 180 mL (Case 1) and 100 mL (Case 2), including urine from the pelvic resected stump, and a 100-mL blood transfusion was required in Case 1, whereas none was needed in Case 2. In Case 1, nine sutures were necessary for hemostasis of the resected stump. In Case 2, there was good demarcation between the lesion and the intact tissue after the vessels supplying the lesion were ligated, which decreased the total warm ischemia time and bleeding amount. The hospital stay was 7 days (Case 1) and 15 days (Case 2), which was almost equal to the average hospital stay for open nephrectomy without chemotherapy at our hospital (10 days). The hypertension seen in Case 2 was cured a year after the surgery. The lesion was not exposed during the operation in either case, which was also checked by an intraoperative frozen section, and the microscopic features included cysts lined with cuboidal cells that were separated by fibrous septae. There was no sign of malignancy; thus, the lesion was consistent with CN (Fig. 4). Fluid accumulation was detected at the resected stump in both cases, but diminished within a month. In addition, both cases showed residual renal function that was approximately one-fifth of that for the intact side and no evidence of residual tumors after 1 year (Fig. 5).
Discussion
Although the etiology of CN is uncertain, eight diagnostic criteria have been presented for these lesions, including unilateral involvement, solitary lesion, multilocular lesion, no communication with the renal pelvis, absence of communication among cysts, loculi lined by epithelium, intralocular septa devoid of renal parenchyma, and normal residual renal tissue, if present. 1 However, some cases present with bilateral lesions or communication with the renal pelvis.2,6,10 Among the differential diagnoses, we could exclude Wilms' tumor with multifocal cystic changes because it presents with solid components in most cases as well as congenital mesoblastic nephroma owing to its indistinct boundary. However, differentiation between CN and CPDN cannot be determined by clinical symptoms or preoperative imaging. 3 On the other hand, CN and CPDN are considered relatively mature variants of cystic Wilms' tumor, with CN standing at the most favorable end and CPDN at the second of the spectrum. 11 Because maturation level could vary within the tumor and malignant tissues could be localized to some portion of the tumor, complete resection is necessary to make a correct diagnosis and to avoid recurrence.
Concerning the frequency of CN and CPDN, both are quite rare: CN accounts for 0.56%–2.4%,7,12,13 and CPDN accounts for 0.5%–0.56%7,14 of all primary renal neoplasms in children. However, according to the literature, both CN patients and stage I CPDN patients have a 100% survival rate with complete resection alone.7,14–16 Therefore, primary resection is recommended with the goal of completely eradicating the tumor while preserving as much normal renal tissue as possible. Because CN is well demarcated, solitary, and noncommunicating with the renal pelvis, partial nephrectomy has been recommended.2,4–7 However, it must be noted that in the case of CPDN, intraoperative tumor spill will result in a higher tumor stage and require a more aggressive therapy.
Laparoscopic partial nephrectomy has been performed for duplication anomalies in children.17–22 In contrast, laparoscopic partial nephrectomy has been performed for small renal malignant tumors in adults. 23 Nevertheless, renal tumors in children are usually large at detection, and laparoscopic partial nephrectomy is not indicated. However, laparoscopic partial nephrectomy could be indicated in some cases of CN. Such an indication includes more than one branch of the renal artery supplying the normal renal segment and a tumor that is not protruding from the kidney. Because of the lesion's thin walls, a protruding tumor could easily rupture during a laparoscopic procedure.
For laparoscopic partial nephrectomy, complete tumor resection, hemostasis, and secure sealing of the urinary tract are important. We devised and paid attention to several major points. For complete tumor resection, we repeatedly checked the tumor's exact area and location using a laparoscopic ultrasound probe, which caused lengthening of the operative time. For hemostasis, the renal artery of the affected side was clamped with Laparoscopic bulldog clips® during dissection to improve hemostasis at the renal stump. Clamping the renal vein may be unnecessary because of minimal venous ooze from the pneumoperitoneum and to improve renal preservation.24,25 Although clamping only the renal artery would allow renal perfusion through the vein and might allow longer warm ischemia time, efforts should be made for shortening the warm ischemia time such as the early unclamping technique. 26 Considering that the resected part was quite large in our 2 cases, it was impossible to close the stump with parenchymal suturing. Therefore, we used Beriplast® P and Surgicel® and then covered the stump with pediculate peritoneum for hemostasis, adequate sealing, and fixing the position of the remaining kidney.8,9,27 In addition, we dissected as little normal tissue as possible from the surrounding adhesive tissue to avoid twisting the remaining kidney. In Case 2, which was performed a little while after Case 1, the total warm ischemia time and the bleeding amount were lessened. This might be partly because there was good demarcation between the affected and normal parts and partly because we had become to be able to dissect more efficiently. The residual renal function, which in both cases was about one-fifth of that for the intact side, was comparable to the residual size of the kidney.
In this report, we show that laparoscopic partial nephrectomy is a feasible approach for treating large CNs occupying more than half of the kidney, regardless of whether they are located at the upper or lower pole. It is also necessary to improve our skill or introduce new technology such as surgical navigation to shorten the operative time for this procedure to become the standard one. 28
Footnotes
Disclosure Statement
No competing financial interests exist.