Clinical and Molecular Characteristics and Outcome of Cystic Partially Differentiated Nephroblastoma and Cystic Nephroma: A Narrative Review of the Literature

Simple Summary

Although renal tumors in children are mostly solid masses, cystic renal tumors also occur. The most likely diagnoses for cystic renal tumors include cystic partially differentiated nephroblastoma and cystic nephroma. Since these tumors are rare, limited information on the treatment, clinical and molecular characteristics, and outcome is available. In this review, we aim to summarize all reported patients with cystic partially differentiated nephroblastoma and cystic nephroma. We identified 113 cystic partially differentiated nephroblastoma and 167 cystic nephroma patients. Surgery was the cornerstone of treatment for both tumor types and chemotherapy was generally not recommended. Cystic nephroma was often related to DICER1-mutations and second tumors, whereas cystic partially differentiated nephroblastoma was related to somatic hyperdiploidy, although testing was rare. The outcome for both tumors is favorable. This study provides information for treatment decisions and stresses the importance of a central review of radiology and pathology, as well as referral to a clinical geneticist.

Abstract

In children presenting with a predominantly cystic renal tumor, the most likely diagnoses include cystic partially differentiated nephroblastoma (CPDN) and cystic nephroma (CN). Both entities are rare and limited information on the clinical and molecular characteristics, treatment, and outcome is available since large cohort studies are lacking. We performed an extensive literature review, in which we identified 113 CPDN and 167 CN. The median age at presentation for CPDN and CN was 12 months (range: 3 weeks–4 years) and 16 months (prenatal diagnosis–16 years), respectively. No patients presented with metastatic disease. Bilateral disease occurred in both entities. Surgery was the main treatment for both. Two/113 CPDN patients and 26/167 CN patients had previous, concomitant, or subsequent other tumors. Unlike CPDN, CN was strongly associated with somatic (n = 27/29) and germline (n = 12/12) DICER1-mutations. Four CPDN patients and one CN patient relapsed. Death was reported in six/103 patients with CPDN and six/118 CN patients, none directly due to disease. In conclusion, children with CPDN and CN are young, do not present with metastases, and have an excellent outcome. Awareness of concomitant or subsequent tumors and genetic testing is important. International registration of cystic renal tumor cohorts is required to enable a better understanding of clinical and genetic characteristics.

Management of Renal Cell Carcinoma With Extensive Caval Thrombosis Utilizing a Temporary Atrial Caval Filter Through a Combined Endovascular and Open Surgical Technique

The most common cause of neoplastic thrombotic infiltration of the inferior vena cava is renal cell carcinoma (RCC). In the present report we described a case of a patient with massive RCC and extensive neoplastic thrombosis reaching the retrohepatic tract of the inferior vena cava. After a discussion in a multidisciplinary team meeting we decided to perform a radical nephrectomy with vena cava thrombectomy along with the support of a novel removable vena cava filter in order to avoid thromboembolism during the surgical procedure. Furthermore, a preoperative renal artery embolization with a non-adhesive liquid embolic agent was performed ahead of the surgical procedure in order to reduce the risk of intraoperative bleeding. The surgical procedure performed the day after was based on a hybrid endovascular-surgical approach consisting in nephrectomy, liver derotation, cavotomy with the additional use of a novel temporary caval filter, thus reducing the risk of intraoperative thromboembolic dissemination.

Quantitative spectral CT evaluation of kidney tumors with the stretched-exponential nonlinear regression analysis model

Background

This study aimed to use the stretched-exponential nonlinear regression analysis model to explore the value of the energy spectral curve in the differential diagnosis of clear cell renal cell carcinoma (ccRCC), minimal fat renal angiomyolipoma (RAML), and hypovascular renal cell carcinoma.

Methods

Sixty-five cases with renal tumors were enrolled retrospectively who had undergone a preoperative multiphase spectral CT scan of the kidney in pre-enhance and double-phase enhanced scanning. The normalized iodine concentrations (NIC) of these lesions, normal renal cortex, and psoas major were measured and calculated. The spectral curves of these lesions and normal tissues were analyzed to calculate the stretched-exponential index (α) and b value with the stretched-exponential nonlinear regression analysis model (y=-b·X^α). The differences between α, b value, and NIC of these lesions and normal tissues in pre-enhance and two enhanced phases were compared using one-way ANOVA. The correlation between α, b value, and NIC was evaluated using the Pearson coefficient test, with significance assigned at the 5% level.

Results

There was no significant difference in α value between the groups in pre-enhance scanning. In the Cortical phase (CP), there were no significant differences in NIC and α value between minimal fat RAML and hypovascular renal cell carcinoma, or between ccRCC and the normal renal cortex. However, in the nephrographic phase (NP), a significant difference in α value was found between minimal fat RAML and hypovascular renal cell carcinoma, but no difference in NIC between them. In NP, there were significant differences in NIC and α values between ccRCC and the normal renal cortex. In CP and NP, there were significant differences between the psoas major and other groups in all parameters. For b value, in pre-enhance scanning, there was a significant difference between the psoas major and other groups, and between ccRCC and the normal renal cortex. There was no significant difference between other groups. After enhancement, in CP and NP, significant differences were observed between the psoas major and other groups in b value, but no significant differences were observed between all renal tumors and the normal renal cortex. A linear correlation was found between α values and NIC in CP (r=0.780, P=0.00) and NP (r=0.693, P=0.00). The b values and NIC had a low correlation in CP, with no correlation in NP.

Conclusions

Quantitative spectral CT with the stretched-exponential nonlinear regression analysis model may enhance the differential diagnosis ability for renal tumors. Its clinical value remains to be further explored in other types of soft tissue lesions.

Expression and clinical significance of interleukin-9 in renal tumors

Background

To measure expression levels of interleukin-9 (IL-9) in renal tumors and to determine the clinical significance of those levels.

Methods

Using TCGA database analysis, we found that the expression of IL-9 in renal clear cell carcinoma was significantly down-regulated, and was significantly related to survival. We then verified this using experiments. We enrolled 66 patients who underwent surgical resection of renal tumors between January and December 2018 at the First Affiliated Hospital of Soochow University. Their tumor tissues were paired with adjacent normal tissues and IL-9 expression levels were measured using immunohistochemistry. We determined the correlation of IL-9 expression with clinicopathological features and progression-free survival (PFS).

Results

Expression of IL-9 in renal tumors was significantly lower than in adjacent normal tissues (P<0.0001). There was a significant negative correlation between IL-9 expression levels and R.E.N.A.L. scores (P=0.0277) as well as with differentiation (P=0.0041). However, no significant correlation was found between IL-9 levels and clinicopathological features, including gender (P=0.0716), age (P=0.2566), body mass index (BMI) (P=0.7941), tumor size (P=0.4193) or TNM staging (P=0.5402). PFS time in renal tumor patients with positive IL-9 expression was similar to that of patients with negative IL-9 expression.

Conclusions

IL-9 expression was higher in adjacent normal tissues than in renal tumors. Low expression of IL-9 was detected when R.E.N.A.L. score was high or cell differentiation was poor, suggesting that IL-9 may may play a protective role in renal tumor microenvironments.

Synchronous Renal Dedifferentiated Liposarcoma and Retroperitoneal Well-Differentiated Liposarcoma: A Case Report With Literature Review

Liposarcoma is the most common soft tissue malignancy and usually occurs in the retroperitoneum or the extremities but rarely in the kidney. In this article, we report a case of a 71-year-old female patient who presented with abdominal lump and left flank pain for 1 month. An abdominal contrast-enhanced computed tomography scan demonstrated a 12 cm × 7 cm solid mass arising from the upper pole of left kidney and another 8 cm × 6 cm low-density retroperitoneal mass with fat density. Radical nephrectomy of the left kidney and resection of the retroperitoneal mass were performed. Surprisingly, pathological examination revealed a high-grade sarcoma (with minor lipomatous component) in the left kidney and a retroperitoneal well-differentiated liposarcoma. MDM2 gene amplification was identified by fluorescence in situ hybridization in both tumors, supporting final diagnosis of dedifferentiated liposarcoma of the kidney and well-differentiated liposarcoma of the retroperitoneum.

Outcomes of gasless laparoendoscopic single-port partial nephrectomy in 356 consecutive patients: Feasibility of a clampless and sutureless technique

OBJECTIVES

To investigate the outcomes and feasibilities of gasless laparoendoscopic single-port clampless sutureless partial nephrectomy.

METHODS

We reviewed 356 consecutive patients with primary unilateral non-metastatic renal masses who underwent gasless laparoendoscopic single-port partial nephrectomy (2011-2018), which was performed retroperitoneally using a three-dimensional flexible endoscope, without vascular clamping or renorrhaphy in principle.

RESULTS

The median tumor size was 2.5 cm, and 213 (60%), 105 (29%), and 38 (11%) patients had peripheral, central, and hilar tumors, respectively. Clampless and sutureless partial nephrectomy was accomplished in 337 patients (95%), while eight (2%) and 16 (4%) patients required vascular clamping and renorrhaphy, respectively. The median operative time and blood loss were 220 min and 266 mL, respectively; eight patients (2%) received blood transfusion. Clavien-Dindo grade 3a complications occurred in 27 patients (8%); all these patients had urinary leakage treated with ureteral stent placement, one of whom also developed a postoperative pseudoaneurysm. Among 324 patients diagnosed with renal cell carcinoma, six (2%) had positive surgical margins, and one (0.3%) and seven (2%) developed metastatic and local recurrences, respectively. During a median follow-up of 54 months, no patient died from kidney cancer. The median percent decrease in estimated glomerular filtration rate at 3 months after surgery was 5.7%. No patient experienced postoperative acute renal failure, while one patient with preexisting renal impairment started dialysis at 70 months after surgery.

CONCLUSIONS

Clampless and sutureless partial nephrectomy can be safely accomplished in most patients undergoing gasless laparoendoscopic single-port surgery, yielding favorable oncological and functional outcomes.

Which Is the Best Predictor to Achieve Trifecta in Patients Undergoing Elective Laparoscopic Partial Nephrectomy with Global Hilar Clamping? Comparative Analysis in Patients with Clinical T1a and T1b Renal Tumors

Background: Partial nephrectomy (PN) is the standard of treatment in patients with cT1 renal tumors. Current guidelines recommend PN as a standard of treatment in patients with cT1 renal tumors. However, the commonly accepted criteria for which surgical outcomes are evaluated both functionally and oncologically are not yet clear. The aim of this study was to evaluate compounding factors that affect the operative and functional outcomes for laparoscopic partial nephrectomy (LPN) in patients with cT1 renal tumors. Methods: This study was registered at NCT04213157 for patients who underwent LPN with the diagnosis of clinical T1 renal tumors. Between November 2009 and August 2018, 292 patients were included in the study. The patients were allocated into two groups according to the tumor size: T1a (n = 215) and T1b (n = 77). Demographic features, clinical tumor characteristics, and intraoperative and postoperative outcomes were analyzed. A negative surgical margin, warm ischemia time of <20 minutes, and no postoperative major complications were accepted to achieve the trifecta outcomes. Pentafecta was defined as trifecta criteria plus >90% preservation of baseline renal function (RF) and no stage upgrade of chronic kidney disease at 12 months after surgery. Univariate and multivariate analyses were used to identify factors predicting trifecta and pentafecta. Results: Preoperative variables including age, gender, and baseline RF were similar between the two groups. The warm ischemia time was 13.4 vs 15.9 minutes (P = 0.001). The positive margin rate was 0.9% vs 2.6% (P = 0.284), and the major complication rate was 3.3% vs 2.6% (P = 0.548). The achievement of the trifecta rate was 88.4% vs 75.3% (P = 0.006) and pentafecta rate was 72.6% vs 42.9% (P = 0.001). Multivariate analysis showed that tumor complexity, baseline RF, and diabetes mellitus are independent predictors of achieving pentafecta outcomes. Conclusion: LPN is an effective and reliable method for renal tumors even in T1b with satisfying surgical and functional outcomes.

Outcome of Children with Stage IV Wilms Tumor - Our Experience of 15 Years

Context:

Stage IV Wilms tumor is associated with poor prognosis, and recent changes in management have been suggested based on genetic markers and response to chemotherapy in this subgroup of patients.

Objective:

The objective was to evaluate the outcomes of children with Stage IV Wilms tumor who were managed with the AIIMS-WT-99 protocol.

Materials and Methods:

All the children with Stage IV Wilms tumor who were managed by us from October 2000 to December 2012 were included in the study. All the patients who had received primary treatment elsewhere were excluded from the study. All patients were managed as per the AIIMS-WT-99 protocol. After appropriate investigations, tumors that were deemed resectable underwent an upfront surgery. Unresectable and inoperable tumors received chemotherapy after cytological confirmation of the diagnosis. Chemotherapy was administered as per the NWTS-5 study. Pulmonary and flank radiotherapy was advised to all patients. Patients with poor response to chemotherapy or with recurrence were managed with an alternative chemotherapy regimen. The outcomes that were assessed the 4-year overall survival (OS) and the 4-year event-free survival (EFS).

Statistical Analysis Used:

Kaplan–Meier survival estimates.

Results:

During the study period, 219 patients with Wilms tumor were treated. Of these, 36 (16.4%) had Stage IV disease, and they formed the study group. The 4-year OS was 48% with a mean survival time of 59 months limited to 115 months (95% confidence interval: 41.3–75.9 months). The 4-year EFS was 42.4%. Patients with liver metastases had a poor outcome, whereas patients with good response to chemotherapy had a good outcome.

Conclusion:

Stage IV Wilms had a poor prognosis, and the survival rates in the index study are lower than those quoted in the literature. Although the exact reason for this poor result eludes us, these patients may benefit from the intensification of chemotherapy.

A Case of Arteriovenous Fistula After Kidney Trauma Mimicking Tumor

Renal arteriovenous fistulas are rare complications of kidney injury that are usually caused by penetrating or blunt abdominal trauma, percutaneous or open biopsy, or surgery. We report a case of renal arteriovenous fistula after blunt abdominal trauma of a male patient who had traffic accidents. Computed tomography images show arteriovenous fistula lesion mimicking the tumor of the renal pelvis. Through this case, we present how to identify and avoid being confused in diagnosis as well as introduce its clinical manifestations, imaging, and treatment.

Risk Factors of Ureteral Stenosis After Percutaneous Microwave Ablation of Renal Tumor, a Single-Center Experience

Background

Ureteral stenosis after percutaneous microwave ablation (MWA) of renal tumor is a rare but severe complication, and its risk factors are not apparent.

Purpose

This study aimed to investigate the risk factors for stenosis of ureter after MWA treatment of the renal tumor that is a rare complication.

Materials and Methods

Data of 211 patients who underwent MWA for the treatment of renal tumor were retrospectively analyzed from September 2006 to August 2019. Demographic characteristics, clinical features, ablation parameters, and outcomes were analyzed to find out the potential risk factors of this complication. P < 0.05 is considered significant.

Results

Six of 211 patients developed ureter stenosis, and the rate of this complication is 2.84%. The median time of emergence of hydronephrosis was 226 (range, 3-390) days. Univariate analysis shows the distance between ureter and tumor (P = 0.225) or ablation zone (P = 0.089) is not related to this complication. Postoperative urine routine (red blood cell, P = 0.001; white blood cell, P = 0.035) and R.E.N.A.L. score (P < 0.001) is related to this complication. But after multivariate logistic analysis, only R.E.N.A.L. score (P = 0.004) is associated with this complication. The location and growth pattern of tumor and the energy of ablation were not related to this complication independently.

Conclusion

The stenosis of the ureter after MWA of renal tumor is not associated with the tumor size, location, or the distance between the ureter and tumor and ablation site independently. But R.E.N.A.L. score is associated with ureter stenosis after MWA for the treatment of renal tumor, which combines the information of location, depth, and size of tumor. Preoperative evaluation of the tumor is necessary for avoiding ureter stenosis. Further studies should focus on these risk factors of this complication.

Effectiveness of Nephron Sparing Surgery and Radical Nephrectomy in the Management of Unilateral Wilms Tumor: A Meta-Analysis

Background: Unilateral Wilms tumor is the most common renal malignancy in the pediatric population. Although the onset of surgical intervention like radical nephrectomy has substantially reduced the mortality rate, recent evidence has raised concerns regarding several postoperative complications associated with this procedure. Nephron sparing surgery has been reported to avoid such postoperative complications and have high technical success rate. However, no attempt to date has been made to synthesize the evidence comparing the efficacy of radical nephrectomy and nephron sparing surgery for managing unilateral Wilms tumor. Methods and Results: To metastatistically compare the efficiency of radical nephrectomy with nephron sparing surgery for managing unilateral Wilms tumor, a systematic identification of the literature was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines on four academic databases: MEDLINE, Scopus, EMBASE, and CENTRAL. A meta-analysis comparing renal function (estimated glomerular filtration rate), survival rate, and rate of relapse was performed to compare the efficacy of radical nephrectomy and nephron sparing surgery. Out of 1,283 records, 20 articles including 5,246 children (mean age, 4.3 ± 3.0 years) were included in this review. Radical nephrectomy was performed on 11 of the included studies, whereas nephron sparing surgery was performed on five studies. Two studies compared the efficacy of both interventions. The meta-analysis reveals the beneficial effects of nephron sparing surgery (Hedge's g, 0.76) as compared to radical nephrectomy (-0.16) for the estimated glomerular filtration rate for children with unilateral Wilms tumor. Moreover, higher survivability (0.59) and lesser occurrence of relapse were (-1.0) also reported for cases operated with nephron sparing surgery. Conclusion: The current meta-analysis recommends the use of nephron sparing surgery for unilateral Wilms tumor. The procedure accounts for higher survivability and postoperative renal function and lesser incidence of relapse as compared to radical nephrectomy.

Renal Artery Embolization for Acute Renal Hemorrhage: A Single-Center Experience

Background

Emergency renal artery embolization (RAE) is a useful method in treating renal trauma and bleeding renal tumors. The aim of this study was to evaluate the clinical efficacy and safety of emergency RAE, and factors associated with RAE failure.

Methods

This retrospective study included patients treated with emergency RAE for acute renal hemorrhage between 1 January 2009 and 31 October 2019 in Srinagarind Hospital. The embolization was performed using coils, glues, and/or gel foams. Factors associated with unsuccessful outcomes were analyzed using univariate and multivariate regression analyses.

Results

A total of 94 patients were treated at the center during the study period with the clinical success rate of 91.5%. The most common cause of acute renal hemorrhage was iatrogenic injury (76.5%). Factors associated with unsuccessful RAE according to multivariate analyses were hypertension (adjusted odds ratio [AOR] 24.2) and ruptured tumor/aneurysm (AOR 26.8).

Conclusion

RAE is an effective procedure for acute renal hemorrhage. Hypertension and ruptured tumor/aneurysm were negative predictors for success.

Surgical Planning for Carcinoma in Horseshoe Kidneys Treated with Retroperitoneoscopic Partial Nephrectomy

Background: Horseshoe kidney (HSK) is a common congenital disease. Its incidence ranges from 1 in 400 to 1 in 1000, and it is often associated with chromosomal aneuploidies. Surgical approaches for tumor arising from HSKs are challenging because of the complicated vessel anatomy, poor mobility, and mass location. We report two patients diagnosed with tumors in HSKs who underwent retroperitoneoscopic partial- or heminephrectomy. Case Presentations: Case 1: A 55-year-old woman presented to the hospital complaining of recurrent back pain. A 3.0-cm tumor mass in a HSK and polycystic kidney was revealed on CT. Three-dimensional (3D) imaging revealed a parenchymal fusion in the superior pole of the left moiety of the HSK, supplied by two main arteries from the aorta. The patient underwent retroperitoneoscopic partial nephrectomy using the four-trocar technique. Case 2: A 50-year-old man was referred to the hospital for further examination of a left renal tumor in his HSK discovered on CT. 3D imaging revealed a 3.4-cm mass arising from the left moiety of a HSK with invasion of the left renal sinus. There were five arteries feeding the tumor. The patient underwent retroperitoneoscopic heminephrectomy after embolization of the main artery supplying the tumor, guided by digital subtraction angiography with the four-trocar technique. Conclusion: Retroperitoneoscopic surgical approaches are feasible for resection of tumors from HSKs. The option of retroperitoneoscopic partial- or heminephrectomy depends on the location and blood supply of the tumor.

Simulated accuracy assessment of small footprint body-mounted probe alignment device for MRI-guided cryotherapy of abdominal lesions

PURPOSE

Magnetic resonance imaging (MRI)-guided percutaneous cryotherapy of abdominal lesions, an established procedure, uses MRI to guide and monitor the cryoablation of lesions. Methods to precisely guide cryotherapy probes with a minimum amount of trial-and-error are yet to be established. To aid physicians in attaining precise probe alignment without trial-and-error, a body-mounted motorized cryotherapy-probe alignment device (BMCPAD) with motion compensation was clinically tested in this study. The study also compared the contribution of body motion and organ motion compensation to the guidance accuracy of a body-mounted probe alignment device.

METHODS

The accuracy of guidance using the BMCPAD was prospectively measured during MRI-guided percutaneous cryotherapies before insertion of the probes. Clinical parameters including patient age, types of anesthesia, depths of the target, and organ sites of target were collected. By using MR images of the target organs and fiducial markers embedded in the BMCPAD, we retrospectively simulated the guidance accuracy with body motion compensation, organ motion compensation, and no compensation. The collected data were analyzed to test the impact of motion compensation on the guidance accuracy.

RESULTS

Thirty-seven physical guidance of probes were prospectively recorded for sixteen completed cases. The accuracy of physical guidance using the BMCPAD was 13.4 ± 11.1 mm. The simulated accuracy of guidance with body motion compensation, organ motion compensation, and no compensation was 2.4 ± 2.9 mm, 2.2 ± 1.6 mm, and 3.5 ± 2.9 mm, respectively. Data analysis revealed that the body motion compensation and organ motion compensation individually impacted the improvement in the accuracy of simulated guidance. Moreover, the difference in the accuracy of guidance either by body motion compensation or organ motion compensation was not statistically significant. The major clinical parameters impacting the accuracy of guidance were the body and organ motions. Patient age, types of anesthesia, depths of the target, and organ sites of target did not influence the accuracy of guidance using BMCPAD. The magnitude of body surface movement and organ movement exhibited mutual statistical correlation.

CONCLUSIONS

The BMCPAD demonstrated guidance accuracy comparable to that of previously reported devices for CT-guided procedures. The analysis using simulated motion compensation revealed that body motion compensation and organ motion compensation individually impact the improvement in the accuracy of device-guided cryotherapy probe alignment. Considering the correlation between body and organ movements, we also determined that body motion compensation using the ring fiducial markers in the BMCPAD can be solely used to address both body and organ motions in MRI-guided cryotherapy.

Liver metastasis at diagnosis in children with nephroblastoma enrolled in SIOP2001 protocol: A French multicentric study

BACKGROUND

Liver metastases are rare in children with Wilms tumor (WT), and their impact on the outcome is unclear.

PATIENTS AND METHODS

The French cohort of patients with WT presenting liver metastases at diagnosis and enrolled in the International Society of Pediatric Oncology (SIOP) 2001 study was reviewed.

RESULTS

From 2002 to 2012, 906 French patients were enrolled in the SIOP2001 trial. Among them, 131 (14%) presented with stage IV WT and 18 (1.9%) had liver metastases at diagnosis. Isolated liver metastases were displayed in four of them. After preoperative chemotherapy, persistent liver disease was reported in 14/18 patients, and 13 of them underwent metastasectomy after nephrectomy. In resected liver lesions, the same histology of the primary tumor was reported for three patients, blastemal cells without anaplasia were identified in one patient with DA-WT, and post-chemotherapy necrosis/fibrosis was identified for the other 10 patients. For the four patients who had liver and lung surgery, both sites had nonviable cells with post-chemotherapy necrosis/fibrosis. Six patients had hepatic radiotherapy. Sixteen patients achieved primary complete remission and were alive at the last follow-up (median follow-up: 6.4 years). The only two deceased patients presented diffuse anaplasia histology. The five-year EFS and OS were 83% (60%-94%) and 88% (66%-97%), respectively.

CONCLUSION

Liver involvement does not appear to be an adverse prognostic factor in metastatic WT. The role of hepatic surgery and radiotherapy remains unclear, and should be carefully considered in case of persistent liver metastases, according to histology and radiological response to other metastatic sites.

Predictive Value of In Vivo MR Spectroscopy With Semilocalization by Adiabatic Selective Refocusing in Differentiating Clear Cell Renal Cell Carcinoma From Other Subtypes

OBJECTIVE. The purpose of this study is to evaluate the diagnostic value of in vivo MR spectroscopy (MRS) with semilocalization by adiabatic selective refocusing (semi-LASER MRS) in differentiating clear cell renal cell carcinoma (RCC) from the non-clear cell subtype. SUBJECTS AND METHODS. Sixteen patients with biopsy-proven RCC or masses highly suspicious for RCC were prospectively recruited to participate in the study. Single-voxel ¹H spectra were acquired using a 3-T MRI system, with a semi-LASER sequence acquired for renal tumors in 14 patients and for healthy renal tissue (control tissue) in 12 patients. Offline processing of the MR spectra was performed. MRI and spectra analysis were performed independently by radiologists who were blinded to the reference histopathologic findings. RESULTS. Semi-LASER MRS was diagnostic for nine of 11 patients (82%) with histopathologically proven clear cell RCC, showing a strong lipid peak in seven patients and a weaker lipid resonance in two others, whereas control spectra showed weakly positive findings in only one patient. MRS findings were negative for lipid resonance in two of three patients (67%) with non-clear cell tumors and were weakly positive in another patient. Semi-LASER MRS had a high sensitivity and positive predictive value of 82% and 90%, respectively, in addition to a specificity of 67%, a negative predictive value of 50%, and overall accuracy of 79% for the detection of clear cell RCC. Lipid resonance was detected by MRS for four of six clear cell RCCs with no intravoxel fat on chemical-shift MRI. CONCLUSION. The preliminary results of the present study show that semi-LASER MRS is promising for the noninvasive discrimination of clear cell RCC from non-clear cell RCC on the basis of detection of lipid resonance and that it provides an incremental yield compared with chemical-shift MRI.

Evaluation of the MR and pathology characteristics immediately following percutaneous MR-guided microwave ablation in a rabbit kidney VX2 tumor implantation model

Purpose: This study aimed to evaluate the immediate efficacy of magnetic resonance (MR)-guided microwave ablation (MWA) in rabbit kidneys implanted with VX2 tumors.Materials and methods: MR-guided MWA was performed in eight VX2 tumor-bearing rabbits. MR images after ablation were obtained and analyzed. The differences between the tissue specimens and MR images obtained after ablation were compared.Results: On the three-dimensional volumetric interpolated breath-hold T1-weighted (3D-VIBE-T1WI) sequence, a low signal intensity indicated the primary tumor at the center of the ablation area, which was surrounded by a peripheral high-signal area. The signal for the primary tumor in the fast spin-turbo spin-echo T2-weighted (FS-TSE-T2WI) sequence was lower than before, and the ablation zone showed a low signal that completely covered the primary tumor. There was no significant difference in volume among the low-signal areas of the primary tumor on FS-TSE-T2WI before MWA, the central low-signal area on 3D-VIBE-T1WI after MWA, and the tumor coagulation necrosis area on the tissue specimens (p > 0.05). No significant difference was found in the volume of ablation zones among the tissue specimens, the high-signal area around the lesion on the 3D-VIBE-T1WI sequence, and the low-signal area covering the lesion on the FS-TSE-T2WI sequence (p > 0.05).Conclusion: Magnetic resonance imaging (MRI) is an effective method for immediate efficacy evaluation of rabbit renal VX2 tumors after MWA and can serve as a valuable reference for the clinical assessment of post-ablative renal tumors.

Robot-assisted versus laparoscopic partial nephrectomy for anatomically complex T1b renal tumors with a RENAL nephrometry score ≥7: A propensity score-based analysis

Objectives

To present the perioperative, functional, and oncological outcomes of robot‐assisted partial nephrectomy (RPN) compared with laparoscopic partial nephrectomy (LPN) for anatomically complex T1b renal tumors with RENAL nephrometry scores ≥7.

Patients and methods

One hundred and seventy patients, during the study period, were retrospectively reviewed in our analysis according to inclusion criteria. Propensity score matching (PSM) (1:1) method was applied to impose restrictions on the potential baseline confounders. The comparisons of perioperative and functional outcomes between the RPN and LPN groups were conducted and analyzed after PSM, Kaplan‐Meier analyses were performed to assess the differences about oncological outcomes between the two groups before and after PSM.

Results

One hundred and nine and 61 T1b renal tumors with RENAL scores ≥7 were identified in the LPN and RPN groups, respectively. All significant differences in baseline characteristics disappeared after PSM. Except for 3 patients missing an appropriate pair, all the patients in the RPN group were successfully matched to 58 patients in the LPN group in a 1:1 ratio. Within the matched cohort, the RPN group was related to a significantly shorter mean operating time (OT) (P = .040), shorter mean warm ischemia time (WIT) (P = .023), and shorter median postoperative hospital stay (P = .023). The possibilities of surgical conversion, postoperative complication, and positive surgical margin were similar in the LPN and RPN groups. And there was also no significant difference in the pathological, renal functional, and oncological outcomes between the two series.

Conclusions

For patients with anatomically complex T1b renal tumors with a RENAL nephrometry score ≥7, RPN had an advantage over LPN in reducing OT, WIT, and postoperative hospital stay length without increasing the risk of complications and weakening the oncological control, while the two surgical methods were similar in renal functional preservation.

Robot-assisted retroperitoneal laparoscopic partial nephrectomy without hilar occlusion VS classic robot-assisted retroperitoneal laparoscopic partial nephrectomy: A retrospective comparative study

To discuss the feasibility, safety, and effectiveness of off-clamp robotic partial nephrectomy via retroperitoneal approach and provide data for evidence based medicine in the surgical treatment of renal tumor.The clinical data was documented and compared between robotic retroperitoneal partial nephrectomy with and without hilar occlusion (clamp group and off-clamp group) performed between January 1, 2015 and December 31, 2017.Six-months post-operative renal function was superior in the off-clamp group compared with clamp group, while long-term results remained to be elucidated. No significant difference in post-operative hospital stay was found between the 2 groups. Estimated blood loss in off-clamp group was significantly higher than clamp group, while no significant difference was found in transfusion rate.Off-clamp robotic partial nephrectomy via retroperitoneal approach is a safe and effective technique for the removal of renal tumor while the indication of surgery is strictly limited to small (<4 cm) and exophytic renal tumor.

Clinicopathologic analysis of renal epithelioid angiomyolipoma: Consecutively excised 23 cases

Renal epithelioid angiomyolipoma (eAML) is considered a malignant variant of angiomyolipoma (AML). From 2001 to 2016, a total of 570 patients were diagnosed with renal AML in Linko Chang Gung Memorial Hospital, Taiwan, including 23 cases of renal eAML. All 23 eAML cases were made up of at least 10% of epithelioid cells histologically. Three of these cases were found with multiple tumors. Two cases developed distant metastasis: one had mediastinal lymph nodes and bilateral lung metastasis; the other one had tumor recurrence over liver and retroperitoneum 1 year after radical nephrectomy. They were then divided into invasive (n = 5) and noninvasive (n = 18) groups according to their clinical behavior. The invasive group showed more severe nuclear atypia and higher rates in tumor necrosis. There was statistically no significance in relation to a patient's age, tumor size, and mitotic count between two groups. After conducting a series of studies, we suggest treating eAML with the guideline of renal cell carcinoma.

The Association Between hMLH1 and hMSH2 Polymorphisms and Renal Tumors in Northeastern China

Aim: Although hMLH1 and hMSH2 are closely associated with the development and drug resistance of multiple types of tumors, their role in renal tumors remains unclear. This study was designed to examine the relationship between renal tumor development and polymorphisms in the hMLH1 and hMSH2 genes. Methods: The study included 180 patients with renal tumors that were confirmed by pathological examination and 199 healthy controls. The clinical and pathological stages of the tumor samples were determined, and DNA was extracted from the peripheral blood of the subjects. Polymorphisms in the hMLH1 and hMSH2 loci were identified using the 1000 genomes database and the multiplex ligase detection method. Correlation analyses was performed using single nucleotide polymorphism tests. Results: 88.9% (160/180) of the tumor specimens were identified as clear cell renal cell carcinoma (CCRC) and 89.4% (161/180) were stage I carcinomas. Three hMLH1 and nine hMSH2 polymorphic sites were identified, and the frequency of the AA genotype of the hMSH2 rs2303424 variant was found to be significantly higher in the renal tumor group (odds ratio [OR] = 1.37, 95% confidence interval [CI]: 1.02-1.86) in the additive model (p = 0.029), the recessive model (p = 0.005), and codominant model (p = 0.02). Multiple testing corrections were performed and the differences between the clear cell carcinoma and control samples remained significant. Compared with the controls, the distribution of the GG genotype of the hMSH2 rs11886591 locus was significantly higher in the clear cell carcinoma group (OR = 0.80, 95% CI: 0.59-1.10, p = 0.04) after multiple testing corrections in the dominant model. Conclusion: The AA genotype at the rs2303424 locus and GG genotype at rs11886591 locus of the DNA repair gene hMSH2 were closely associated with the development of renal tumors. Further studies are needed on larger cohorts to confirm this correlation.

Indications and results of diagnostic biopsy in pediatric renal tumors: A retrospective analysis of 317 patients with critical review of SIOP guidelines

OBJECTIVES

According to the Renal Tumor Study Group (RTSG) of the International Society of Paediatric Oncology (SIOP), diagnostic biopsy of renal tumors prior to neoadjuvant chemotherapy is not mandatory unless the presentation is atypical for a Wilms tumor (WT). This study addresses the relevance of this strategy as well as the accuracy and safety of image-guided needle biopsy.

METHODS

Clinical, radiological, and pathological data from 317 children (141 males/176 females, mean age: 4 years, range, 0-17.6) consecutively treated in one SIOP-affiliated institution were retrospectively analyzed.

RESULTS

Presumptive chemotherapy for WT was decided for 182 patients (57% of the cohort), 24 (8%) were operated upfront, and 111 (35%) were biopsied at diagnosis. A non-WT was confirmed after surgery in 5/182 (3%), 11/24 (46%), and 28/111 (25%), respectively. Age at diagnosis was the most commonly (46%) used criterion to go for biopsy but a nine-year threshold should be retrospectively considered more relevant. Tumor volumes of clear cell sarcoma of the kidney and WT were significantly higher than those of other tumors (P = 0.002). The agreement between core-needle biopsy (CNB) and final histology was 99%. No significant morbidity was associated with CNB.

CONCLUSION

The use of SIOP criteria to identify patients eligible for presumptive WT neoadjuvant chemotherapy or upfront surgery avoided biopsy in 65% of children and led to a 97% rate of appropriate preoperative chemotherapy. Image-guided CNB is a safe and accurate diagnostic procedure. The relevance of SIOP biopsy criteria might be improved by using an older age threshold (9 years instead of 6 years) and by adding initial tumor volume.

Blastemal predominant type Wilms tumor in Japan: Japan Children's Cancer Group

BACKGROUND

Persistence of blastemal components after chemotherapy is a marker of poor outcome in Wilms tumor (WT). Recent reports from local Japanese areas have described pre-chemotherapy blastemal predominant type WT to also be a risk factor for relapse. The significance, however, of blastemal predominant WT remains to be evaluated in a larger study. This study retrospectively evaluated the prognostic significance of pre-chemotherapy blastemal predominant type WT in the Japan Wilms tumor Study (JWiTS) trials.

METHODS

The JWiTS trial (1996-2013) was a prospective, single-arm study. The outcomes of blastemal predominant type WT were retrospectively evaluated compared with non-blastemal type WT excluding anaplasia between 1996 and 2013. Relapse-free survival (RFS) and overall survival (OS) were estimated.

RESULTS

Of 319 primary renal tumors diagnosed by the central pathology review system, advanced stage of pre-chemotherapy blastemal predominant type WT (n = 53; 16.1%) occurred more frequently in older children than non-blastemal type WT (n = 225), and was especially frequent in female patients registered in the JWiTS trials. No significant difference in 10 years RFS and OS (78.8% vs 84.5; P = 0.201) or in 10 years RFS and OS (89.3% vs 93.5; P = 0.45) was seen between pre-chemotherapy blastemal predominant type and non-blastemal type WT.

CONCLUSIONS

Relapse-free survival and OS are not significantly different between pre-chemotherapy blastemal predominant type and non-blastemal type WT.

Long-term renal function following zero ischemia partial nephrectomy

Partial nephrectomy (PN), also known as nephron sparing surgery, is considered as the first-line treatment in small renal masses, especially in T1/2 tumors, and is applied as a standard treatment in advanced centers. The main expected outcomes from an ideal PN are surgical margin negativity, minimal impairment in renal function, and any surgical complications. Many authors have defined PN techniques as “zero ischemia partial nephrectomy”, where surgery is performed without clamping the main renal artery in order to protect the renal parenchyma from ischemic injury. Various PN techniques employed by surgeons include: selective or segmental renal artery clamping technique; off-clamp, clampless, or unclamped technique; preoperative superselective transarterial tumor embolization technique; sequential/modified sequential preplaced suture renorrhaphy technique, radio frequency ablation-assisted technique, and combination of these techniques. The common goal of all these techniques is to provide zero ischemia without hilar clamping. This systematic review focuses on the long-term functional outcomes of PNs performed by zero ischemia techniques.