Wilms tumor and multicystic dysplastic kidney disease

Practical Approach to Congenital Anomalies of the Kidneys: Focus on Anomalies With Insufficient or Abnormal Nephron Development: Renal Dysplasia, Renal Hypoplasia, and Renal Tubular Dysgenesis

Congenital anomalies of the kidney and urinary tract (CAKUT) accounts for up to 30% of antenatal congenital anomalies and is the main cause of kidney failure in children worldwide. This review focuses on practical approaches to CAKUT, particularly those with insufficient or abnormal nephron development, such as renal dysplasia, renal hypoplasia, and renal tubular dysgenesis. The review provides insights into the histological features, pathogenesis, mechanisms, etiologies, antenatal and postnatal presentation, management, and prognosis of these anomalies. Differential diagnoses are discussed as several syndromes may include CAKUT as a phenotypic component and renal dysplasia may occur in some ciliopathies, tumor predisposition syndromes, and inborn errors of metabolism. Diagnosis and genetic counseling for CAKUT are challenging, due to the extensive variability in presentation, genetic and phenotypic heterogeneity, and difficulties to assess postnatal lung and renal function on prenatal imaging. The review highlights the importance of perinatal autopsy and pathological findings in surgical specimens to establish the diagnosis and prognosis of CAKUT. The indications and the type of genetic testing are discussed. The aim is to provide essential insights into the practical approaches, diagnostic processes, and genetic considerations offering valuable guidance for pediatric and perinatal pathologists.

The Outcome of Multicystic Dysplastic Kidney Disease Patients at King Abdulaziz Medical City in Riyadh

Background Multicystic dysplastic kidney (MCDK) is a type of kidney dysplasia consisting of many irregular, various-sized cysts divided by dysplastic renal tissue, which negatively impacts kidney function. MCDK is one of the most common renal congenital disorders seen in antenatal ultrasounds. The typical prognosis of MCDK is complete or partial involution that starts antenatally and continues postnatally. The aim of the study was to shed light on the overall outcome of patients with MCDK. Methods We retrospectively collected data on MCDK patients from 2016 until 2022 at King Abdulaziz Medical City, Ministry of National Guard Health Affairs in Saudi Arabia, Riyadh. The data included the recording of epidemiological data, radiological and laboratory reports, and the presence of urological or non-urologically associated anomalies. Results A total of 57 patients with MCDK were reviewed. Seven of them were excluded due to the diagnosis of bilateral MCDK, which was incompatible with life. Of the remaining 50 patients, the right kidney was affected in 52% of them. Most patients were diagnosed antenatally (98%). The mean duration of follow-up for the study was 48 months. Vesicoureteral reflux (VUR) was detected in 22% of the total sample. Overall, 90% of the patients underwent kidney involution. A small percentage had genitourinary anomalies (20%), while a larger percentage (48%) had extrarenal abnormalities. Conclusion Multicystic dysplastic kidney disease is relatively common in children. The prognosis is affected by the presence of genitourinary and non-genitourinary anomalies. Patients have an overall good prognosis with conservative management. Antenatal screening, diagnosis, and long-term nephrological follow-up are essential for the optimal management of patients.

Expending the Phenotypic Spectrum of Encephalocraniocutaneous Lipomatosis: About a Prenatal Case With Complete Autopsy

Encephalocraniocutaneous lipomatosis (ECCL) or Haberland syndrome (MIM #613001) is a rare congenital neurocutaneous disorder. It is characterized by unilateral ocular, cutaneous and central nervous system anomalies. Key clinical features include hairless fatty tissue nevus of the scalp, choristoma of the eye and intraspinal and intracerebral lipomas. We report one of the first cases diagnosed after termination of pregnancy at 35 WG, including antenatal and post-mortem imaging, complete autopsy and genetic analysis. Prenatal ultrasound and MRI of the third trimester showed multifocal spinal lesions and left lateral cerebral ventriculomegaly with cerebral atrophy. Diagnosis of ECCL was suggested at complete autopsy which revealed nevus psiloliparus of the scalp, facial hamartomas and intracranial and spinal lipomas. In addition, our case also exhibited a cardiac rhabdomyoma and a multicystic dysplastic kidney, both never reported to date in this syndrome. ECCL was confirmed by the identification of a postzygotic FGFR1 mutation. We reviewed the literature and discuss the pathogenesis of this syndrome.

Unusual association of Wilms' tumor with cystic diseases of kidney: A pathologic surprise

Wilms' tumor (or nephroblastoma) is the most common renal malignancy in the pediatric population which consists of blastemal, epithelial, and stromal elements in variable proportions. The occurrence of renal cysts in children and infants is a rare phenomenon and is possibly an outcome of developmental aberrations in mesonephric blastema. The coincidental association of nephroblastoma with renal cysts is a very rare finding. Here, we describe two cases of Wilms' tumor with an unusual association between glomerulocystic kidney disease and multicystic dysplastic kidney.

Congenital Anomalies of the Kidney and Urinary Tract: A Clinical Review

Purpose of review

This review highlights the most common congenital anomalies of the kidney and urinary tract (CAKUT) that are encountered in pediatric practices. CAKUT are the most common cause of prenatally diagnosed developmental malformations and encompass a spectrum of disorders impacting lower urinary tract development as well as kidney development and function. In pediatric and adolescent populations, developmental abnormalities are the leading cause of end-stage kidney disease. The goal of this review is to provide pediatric providers a framework for appropriate clinical management as well as highlight when referral to subspecialty care is needed.

Recent findings

While the exact etiologies of CAKUT are not completely defined, new evidence demonstrates that genetic and molecular changes impact embryonic kidney and urinary tract development. As a result, phenotypes and clinical outcomes may be affected.

Summary

Because pediatric providers provide front-line care to children and adolescents with developmental kidney and urinary tract anomalies, updated knowledge of CAKUT pathogenesis, embryology, clinical management, and patient outcomes is needed. This manuscript reviews CAKUT etiologies and essential diagnostic, prognostic, and management strategies.

Evidence-based treatment of multicystic dysplastic kidney: a systematic review

OBJECTIVES

There is a lack of a standardised protocol for the investigation and non-operative management of paediatric multicystic dysplastic kidney (MCDK). Institutional protocols for non-operative management remain essentially ad hoc. The primary outcome of this systematic review is to establish the incidence of hypertension associated with an MCDK. The secondary outcome is to determine the malignancy risk associated with an MCDK. The tertiary outcome is to assess the rate of MCDK involution. Subsequent to these, an evidence-based algorithm for follow-up is described.

METHODOLOGY

A systematic review of all relevant studies published between 1968 and April 2017 was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies were identified by specific inclusion and exclusion criteria, all of which included data relevant to the primary, secondary and tertiary outcomes. Hypertension was defined as systolic blood pressure greater than the 95th centile for gender, age and height centile. Subset analysis was performed for hypertension associated with an MCDK.

RESULTS

The primary outcome measure revealed a 3.2% (27/838) risk of developing hypertension associated with an MCDK. The secondary outcome measure noted a 0.07% malignancy risk (2/2820). The tertiary outcome measure established that 53.3% (1502/2820) had evidence of involution of the dysplastic kidney. A total of 44 cohort studies (2820 patients) were analysed.

CONCLUSION

Given the low risk of hypertension and malignancy, which is similar to the general population, the current conservative non-operative pathway is an appropriate management strategy. An algorithm to help support clinicians with ongoing management is proposed.

Nuclear Medicine in Pediatric Nephro-Urology: An Overview

In the context of ante-natally diagnosed hydronephrosis, the vast majority of children with a dilated renal pelvis do not need any surgical treatment, as the dilatation resolves spontaneously with time. Slow drainage demonstrated at Tc-99m-mercaptoacetyltriglycine (MAG3) renography does not necessarily mean obstruction. Obstruction is defined as resistance to urinary outflow with urinary stasis at the level of the pelvic-ureteric junction (PUJ) which, if left untreated, will damage the kidney. Unfortunately this definition is retrospective and not clinically helpful. Therefore, the identification of the kidney at risk of losing function in an asymptomatic patient is a major research goal. In the context of renovascular hypertension a DMSA scan can be useful before and after revascularisation procedures (angioplasty or surgery) to assess for gain in kidney function. Renal calculi are increasingly frequent in children. Whilst the vast majority of patients with renal stones do not need functional imaging, DMSA scans with SPECT and a low dose limited CT can be very helpful in the case of complex renal calculi. Congenital renal anomalies such as duplex kidneys, horseshoe kidneys, crossed-fused kidneys and multi-cystic dysplastic kidneys greatly benefit from functional imaging to identify regional parenchymal function, thus directing further management. Positron emission tomography (PET) is being actively tested in genito-urinary malignancies. Encouraging initial reports suggest that F-18-fluorodeoxyglucose (FDG) PET is more sensitive than CT in the assessment of lymph nodal metastases in patients with genito-urinary sarcomas; an increased sensitivity in comparison to isotope bone scans for skeletal metastatic disease has also been reported. Further evaluation is necessary, especially with the promising advent of PET/MRI scanners. Nuclear Medicine in paediatric nephro-urology has stood the test of time and is opening up to new exciting developments.

Postnatal sonographic spectrum of prenatally detected abdominal and pelvic cysts

OBJECTIVE

The purpose of this article is to illustrate the sonographic findings of a spectrum of neonatal abdominal and pelvic cystic lesions.

CONCLUSION

Neonatal abdominal and pelvic cystic lesions can arise from many organs, and they have a broad differential diagnosis. Distinctive sonographic findings may be present and can help establish the correct cause and guide proper management.

Multicystic dysplastic kidney: Impact of imaging modality selection on the initial management and prognosis

OBJECTIVE

To evaluate the impact of imaging modalities on the evaluation and prognosis of children with multicystic dysplastic kidney (MCDK) disease.

PATIENTS AND METHODS

A retrospective analysis of all children with MCDK diagnosed from 2004 until 2012 was performed. The study included 63 patients for whom all postnatal imaging modalities were available: renal bladder ultrasound (RBUS), dimercaptosuccinic acid scan (DMSA) and voiding cystourethrogram (VCUG). Cases with major congenital abnormalities or incomplete data were excluded. Abnormalities in the contralateral kidney and the fate of MCDK were also addressed.

RESULTS

At diagnosis, the average age was four-and-a-half months. The majority of cases were detected antenatally (87%). Postnatal RBUS and DMSA scans established the diagnosis of MCDK in 92% and 98% of patients, respectively. DMSA showed photopenic areas in the contralateral kidneys in 10% of patients; all of them had hydronephrosis and were confirmed to have vesicoureteral reflux (VUR). Contralateral VUR was detected in 16 patients; 63% of them had hydronephrosis. After a mean follow-up of three-and-a-half years, involution occurred in 62% of patients and the involution rate was inversely proportional to the initial size.

CONCLUSIONS

The classical appearance of MCDK on RBUS was sufficient to establish the diagnosis in most patients. DMSA scan was more accurate in confirming the diagnosis and evaluating the contralateral kidney. Selective screening for VUR in patients with contralateral hydronephrotic kidney should be considered.

Single-stage surgical approach in complicated paediatric ureteral duplication: surgical and functional outcome

PURPOSE

Surgical approach to children with complicated ureteral duplication is discussed controversially. Our aim was to determine the outcome of children with complicated renal duplication undergoing a single-stage surgical approach with laparoscopic partial nephrectomy and open bladder reconstruction.

METHODS

Data of patients from 2004 to 2008 were investigated retrospectively. Outcome was analyzed in terms of postoperative course, renal function, urinary tract infection and functional voiding.

RESULTS

Thirteen patients were treated with laparoscopic partial nephrectomy and reconstruction of the lower urinary tract in a single-stage approach. Median age at operation was 15 months (2-63 m). One girl had a renal triplication. 7/13 patients presented with an ectopic ureterocele, two with an ectopic ureter, severe vesicoureteral reflux occurred in 6 patients. All patients had non-functioning renal moieties. Mean operative time was 239 min (129-309; SD 50). One re-operation was necessary 4 years after primary surgery due to a pole remnant. All patients had uneventful recoveries without evidence of recurrent UTI. Postoperative 99mTc-MAG3 scans showed no significant reduction of partial renal function (p = 0.4), and no signs of obstruction (p = 0.188). During a median follow-up of 60 months (49-86), dysfunctional voiding occurred in one patient.

CONCLUSIONS

In children with complicated ureteral duplication a definitive single-stage procedure is feasible and shows excellent functional results.

Unilateral multicystic dysplastic kidney: does initial size matter?

BACKGROUND

We report the long-term follow-up of children with antenatally detected unilateral multicystic dysplastic kidney (MCDK) who were followed between 1985 and 2009.

METHODS

Involution rates were documented over time based on the initial size of the MCDK, as documented on postnatal ultrasound (USS), as well as long-term complications and renal function.

RESULTS

In 323 patients (182 male), 10 % of MCDK had involuted, as evidenced on the first postnatal USS, with survival function analysis showing the probability of complete involution to be 35 % in 249 patients by 2 years of age, 47 % in 180 patients by 5 years of age and 62 % in 94 patients by 10 years of age. There was a significant difference in the involution rates of MCKD at the 10-year follow-up between MCDK with an initial size of >5 cm versus MCDK with an initial size of ≤5 cm (p < 0.0001). No patients in the whole cohort developed sustained hypertension or malignancy during a median follow-up of 10.1 years (range 0.3-15.4 years). Median estimated glomerular filtration rate (eGFR) in 76 patients (7 at 5 years, 69 at 10 years) was 93 ml/min/1.73 m(2) (range 46-175 ml/min/1.73 m(2)), with 40 (53%) having an eGFR of between 90 and 140 ml/min/1.73 m(2). Twenty-three (30 %) of the 76 patients at 10 years had normal eGFR (90-140 ml/min/1.73 m(2)) as well as complete involution of the MCDK, compensatory hypertrophy of the contralateral kidney, no proteinuria and no hypertension.

CONCLUSIONS

Larger MCDK at birth are less likely to involute during the first decade of life. However, conservative management remains justified due to the lack of complications. A minority of patients fulfil current criteria for discharge from specialty follow-up at 10 years.

Indications and relative renal function for paediatric nephrectomy over a 20-year period

BACKGROUND

The indications for partial or total nephrectomy for urological reasons are not clearly documented in the paediatric surgical literature and there are only a limited number of publications on this subject.

PURPOSE

In order to clarify the situation in our centre, we reviewed our own indications for nephrectomy over a 20-year period.

METHODS

Medical records of patients who underwent nephrectomy for urological and oncological causes between May 1990 and October 2010 at our centre were retrospectively reviewed. Indications for nephrectomy were noted. Renal function was noted for urological cases.

RESULTS

A total of 357 nephrectomies were undertaken; out of these, 241 cases were for urological causes and 116 for oncological reasons. The majority of total nephrectomies were performed for multicystic dysplastic kidneys, reflux nephropathy, pelvi-ureteric junction obstruction and dysplasia. Eighty-seven patients exhibited no function at the time of nephrectomy. Of the remainder, 17 had <5% function, 18 had 5-10% function, 5 had 10-15% function and 2 patients had 15-20% function.

CONCLUSIONS

This is the largest series of nephrectomies in the paediatric surgery literature to date. The majority of nephrectomies were undertaken for urological conditions with relative renal function of <10% and could not have been usefully preserved in situ. We suggest that kidneys with >10% function should not be routinely removed.

Multicystic dysplastic kidney: our experience in non-surgical management

INTRODUCTION

Although multicystic dysplastic kidney (MDK) is a common renal anomaly, the management of this condition remains controversial. The purpose of this study was to focus on its regression by ultrasound (US) scan for MDK managed conservatively.

MATERIALS AND METHODS

Between 1990 and 2010, 50 children with MDK were retrospectively studied. All patients were submitted to radioisotope scan to confirm the diagnosis, and a micturating cystogram to exclude other uropathies.

RESULTS

Of the 50 patients, 19 underwent nephrectomy, and the other 31 were conservatively managed with clinical and US scan follow-up. The mean follow-up time (range 6 months to 11 years) in the non-operated group was 6.2 years. Of the 31 children with nonsurgical management, 17 (54.8%) showed total involution on US scan, 7 (22.6%) showed a partial regression, and 7 (22.6%) were unchanged at the time of this study. The mean time to complete disappearance on US scan was 2.5 years (1-4 years). No children developed hypertension or tumors.

DISCUSSION

The natural history of MDK is usually benign, but patients must have long-term follow-up with US scan. In addition, many studies confirmed that the disappearance of it on a US scan does not mean a total involution of the affected kidney. We recommend a strict follow-up even when US scan shows an undetectable kidney.

Multicystic dysplastic kidney in children--a need for conservative and long term approach

OBJECTIVE

We retrospectively studied our cases of Multicystic Dysplastic Kidney (MCDK). The review was aimed at identifying the pattern of the disease in Indian Scenario and the required management thereof.

METHODS

We studied the clinical, radiological and nuclear scan findings of 22 patients with unilateral MCDK. They were diagnosed and/or treated in our unit from 1999 to 2007. The diagnosis was achieved by Ultrasound and further confirmed by DMSA scans. Other ancillary investigations like Micturating cystourethrogram were done if indicated. These patients were followed and followup investigations consisted of renal ultrasound, blood pressure measurement, and urinalysis and blood biochemistry

RESULTS

A total of 22 patients (18 boys and 4 girls) with unilateral MCDK were investigated and followed for a mean period of 41 months. MCDK was detected on antenatal ultrasound only in 12(55%) and postnatally in 10(45%) babies. Mean age for postnatal diagnosis was 20 months. Follow up ultrasound revealed complete involution of MCDK in 3 patients and partial regression in 11 patients. The size of dysplastic kidney was unchanged in 4 patients and a further 4 patients underwent nephrectomy. Indications of nephrectomy were parental anxiety in 2, hypertension in 1 and palpable mass in 1.

CONCLUSION

Large proportion (45%) of patients in presented series are diagnosed post natally contrary to western world where more than 80% are diagnosed antenatally. Uncomplicated isolated MCDK carry good prognosis with nephrectomy required in only a few patients. Association with other urological anomalies in ipsilateral/contralateral genitourinary tract is important to identify as they have worse outcome in terms of ultimate renal function. All patients with simple/complex unilateral MCDK should be advised long term follow up for the possible development of hypertension and/or hyper infiltration injury.

Management and etiology of the unilateral multicystic dysplastic kidney: a review

In children, unilateral multicystic dysplastic kidney (MCDK) is one of the most frequently identified urinary tract abnormalities. A variety of proposed etiologies has been associated with the underlying pathogenesis of MCDK. These include genetic disturbances, teratogens, in utero infections, and urinary outflow tract obstruction. From 5-43% of the time, MCDK has associated genito-urinary anomalies, both structural and functional in nature. A review of the literature reveals that involution rates are reported to be 19-73%, compensatory hypertrophy of the contralateral kidney occurs from 24-81% of the time, and estimated glomerular filtration rates (GFRs) (by the Schwartz formula) range from 86-122 ml/min per 1.73 m(2) body surface area. Most authors suggest serial ultrasonography to monitor contralateral growth, routine blood pressure monitoring, and a serum creatinine monitoring algorithm. The risk of hypertension in those with MCDKs does not appear to be greater than that of the general population, and the rates of malignant transformation of MCDK are small, if at all increased, in comparison with those in the general population. If the patient develops a urinary tract infection or has abnormalities of the contralateral kidney, shown on ultrasound, a voiding cystourethrogram is recommended. Finally, the body of literature does not support the routine surgical removal of MCDKs.

Non-surgical management of multicystic dysplastic kidney

OBJECTIVES

To better define the outcome and association of multicystic dysplastic kidney (MCDK) with hypertension, vesico-ureteric reflux (VUR), infection and cancer, as there is no consensus on the management of patients born with MCDK. The risk of cancer has dictated the surgical management of the disease in the past.

METHODS

The Medline database was searched for articles published between 1965 and 2006 and written in the English language, and containing the keywords 'multicystic dysplastic kidney'.

RESULTS

The inclusion criteria were met by 105 reports that were subsequently analysed. Of MCDK, 60% regress or involute within 3 years. About 25% of patients will have VUR into the contralateral kidney, of which 90% is grade <or=3. The risk of urinary tract infection appears to be associated with VUR or coexistent abnormalities rather than the MCDK. The risk of hypertension is no greater than that in the general population and nephrectomy is usually not curative. The overall risk of Wilms' tumour developing in a MCDK is <1 in 2000. All reported Wilms' tumours were identified before 4 years of age and 70% presented as a palpable mass.

CONCLUSIONS

Published reports support the non-surgical management of MCDK. Common practice has been to remove palpable or growing MCDKs, although these represent a very small fraction of MCDKs. In theory, ultrasonographic surveillance until 4 years old might allow the earlier detection of a Wilms' tumour, and decrease the intensity of chemotherapy and improve prognosis. Previous reports do not prove or disprove this concept, and the appropriate frequency of surveillance is not evident.

Renal dysplasia and MRI: a clinician's perspective

Renal dysplasia is a common abnormality in children. The role of MRI in evaluating children with renal dysplasia is evolving. More information is clearly necessary before MRI replaces conventional imaging modalities. In order to appropriately use MRI, the radiologist must have an understanding of the clinical questions that are important in the management of children with renal dysplasia. This review provides background information on renal dysplasia for the pediatric radiologist. The focus is on unilateral disease, especially multicystic dysplastic kidneys, and bilateral dysplasia, which is the most common cause of kidney failure in children. The emphasis is on the important clinical issues, and the potential of MRI as a methodology for providing clinically useful information not otherwise available from other imaging modalities.

Unilateral multicystic dysplastic kidney: long term outcomes

AIMS

To report the long term follow up of children with antenatally detected unilateral multicystic dysplastic kidney (MCDK) with documentation of complications, involution rate with time, and renal function at 10 years.

METHODS

Data were retrieved from a prospective regional registry of patients with MCDK between 1985 and 2004. Children were followed using a common protocol of investigation with follow up ultrasound scans (USS) at 2 (165 patients), 5 (117 patients), and 10 years (43 patients).

RESULTS

Serial USS showed that 33% of the MCDK kidneys had completely involuted at 2 years of age, 47% at 5 years, and 59% at 10 years. No patients developed hypertension, significant proteinuria, or malignancy, but two developed pelviureteric junction obstruction in the contralateral kidney. Twenty seven of 143 children (19%) had vesicoureteric reflux (VUR) (96% mild to moderate VUR) into the contralateral kidney with no difference in the incidence of urinary tract infections or renal scarring between those with or without VUR. The mean estimated glomerular filtration rate (GFR) was 86.4 ml/min/1.73 m2 (range 48-125) in 31 of 43 patients followed to 10 years.

CONCLUSIONS

Conservative management of unilateral MCDK is justified with clinical review and infrequent USS but longer term follow up continues in the 41% still with renal remnants at 10 years and those with impaired GFR. It is suggested that the initial micturating cystogram is deferred unless abnormal USS features are present in the contralateral kidney or ureter.

Indications for nephrectomy in children: what has changed?

OBJECTIVE

To review the indications for nephrectomy in children between 1990 and 2001, at the Starship Children's Hospital, Auckland, New Zealand.

PATIENTS AND METHODS

There were 206 nephrectomies. A retrospective review of the patients' notes was performed. The 12-year period was divided into two halves (1990-1996 and 1996-2001) which were then compared.

RESULTS

The total number of nephrectomies per year significantly increased over the period of the study (11.5 and 22.2 per year for 1990-1995 and 1996-2001, respectively; P<0.05), as did the number of partial nephrectomies (one and 23 for 1990-1995 and 1996-2001, respectively; P<0.01). Multicystic dysplastic kidney (MCDK), Wilms' tumour and vesico-ureteric reflux (VUR) accounted for more than half of the nephrectomies (60% and 68% for 1990-1995 and 1996-2001, respectively). The proportion of nephrectomies performed for these indications did not change (MCDK 25% and 34%, Wilms' 25% and 18%, VUR 16% and 18%, for 1990-1995 and 1996-2001, respectively), but fewer nephrectomies were performed for pelvi-ureteric junction (PUJ) obstruction in the second half of the study period (13% and 4% for 1990-1995 and 1996-2001, respectively; P<0.05).

CONCLUSION

The total number of nephrectomies, including partial nephrectomies, has increased significantly. The decrease in nephrectomies for PUJ obstruction could be accounted for by a more aggressive approach in the management and follow up of prenatally diagnosed hydronephrosis. Of note is that there was no significant change in the proportion of nephrectomies performed for Wilms' tumour, MCDK and VUR.

Collecting duct carcinoma arising from multicystic dysplastic kidney disease

Malignancy arising from a multicystic dysplastic kidney (MCDK) is rare. Most reports are of Wilms' tumor and clear-cell renal cell carcinoma arising from a previously unrecognized MCDK. To our knowledge, no reports have described collecting duct carcinoma arising from MCDK.

Malignant retroperitoneal tumor arising in a multicystic dysplastic kidney of a girl with Schinzel-Giedion syndrome

We report the first case of malignant retroperitoneal tumor arising in a multicystic dysplastic kidney of an 8-year-old girl with Schinzel-Giedion syndrome. Although conservative treatment has been regarded as the standard management for asymptomatic multicystic dysplastic kidney, prophylactic surgical removal should be considered for selected children with potential risk of malignancy.

Predictive factors of ultrasonographic involution of prenatally detected multicystic dysplastic kidney

OBJECTIVE

To evaluate possible predictive factors of involution on ultrasonography (US) or disappearance of a prenatally detected multicystic dysplastic kidney (MCDK).

PATIENTS AND METHODS

Forty-five children with unilateral MCDK detected by prenatal ultrasonography between 1989 and 2002 were analysed. All patients except one had (99m)Tc isotopic scintigraphy to confirm the absence of renal function in the MCDK. All children were managed conservatively with follow-up visits every 6 months, with US 6-monthly during the first 2 years of life and yearly thereafter. Survival was analysed using the Kaplan-Meier method to evaluate the involution of the MCDK, with differences between subgroups assessed using the two-sided log-rank test. Cox's regression model was applied for the multivariate analysis.

RESULTS

The mean (range) follow-up was 50 (12-167) months; in all, 279 ultrasonograms were taken, the mean (range) number per patient being 6 (3-10). US showed partial involution of the MCDK in 30 (67%) cases and complete involution in nine (20%). The absolute MCDK length remained almost unchanged in six children (13%). Univariate analysis showed that four variables were possibly associated with complete involution of the MCDK (gender, impalpable kidney, renal length at admission using two thresholds, 62 and 78 mm). After adjusting by Cox's model only a renal length at diagnosis of <62 mm remained associated with complete involution (relative risk 8, 95% confidence interval 0.98-68; P = 0.05).

CONCLUSION

These results suggest that only a renal length of <62 mm on initial US was predictive of complete involution of the MCDK during the follow-up.

Risk of Wilms' tumour with multicystic kidney disease: a systematic review

BACKGROUND

Children with multicystic kidney disease (MCKD) are increasingly managed conservatively and are followed up throughout childhood because they are perceived to be at increased risk of developing Wilms' tumour. With this risk still poorly defined and somewhat controversial, the strategy and the duration of follow up do not seem to be based on evidence.

METHODS

Systematic review of the literature for all published cohort studies (prospective and retrospective) of children diagnosed to have unilateral MCKD and managed conservatively.

EXCLUSION CRITERIA

bilateral MCKD, nephrectomy (not for malignancy) during the follow up period. We estimated for children with MCKD the probability of developing Wilms' tumour during the follow up period, with 95% CI using the Poisson distribution.

RESULTS

From 26 reviewed studies, no cases of Wilms' tumour developed in 1041 eligible children. The mean probability of a child with unilateral MCKD to develop Wilms' was therefore nil, with a 97.5% upper CI estimated at 0.0035 (or 3.5 per 1000 children).

CONCLUSION

The development of a national or a European registry for children with MCKD would increase the precision of their risk estimate to develop Wilms' tumour. In the meantime, there is no evidence to support any of the different modalities for following up these children by ultrasound, if indeed such a strategy is necessary.

Natural history of multicystic kidney conservatively managed: a prospective study

We report the long-term clinical results of conservative management of children with unilateral multicystic dysplastic kidneys (MCDK). Between 1989 and 2002, 43 children with MCDK detected by prenatal ultrasonography were prospectively followed. At birth, ultrasonography confirmed the prenatal findings in all cases. Patients underwent a radioisotope scan and micturating cystogram in order to confirm the diagnosis and to exclude other uropathies. Follow-up ultrasound (US) examinations were performed at 6-month intervals during the first 2 years of life and yearly thereafter. The mean follow-up time was 42 months (range 12-156 months). Two children developed hypertension during follow-up. In total 257 US scans were performed. The mean number of US scans per patient was 6 (range 3-10). US scans demonstrated partial involution of the MCDK in 30 (70%) cases and complete involution in 8 (19%). The absolute MCDK length remained almost unchanged in 5 children (11%). The estimated median time of complete involution of the MCDK was 122 months [95% confidence interval (CI)=86-158 months]. A total of 33 (76.7%) contralateral kidneys underwent compensatory hypertrophy, reaching a renal length above the 95th percentile during follow-up. The estimated median time for the occurrence of compensatory hypertrophy was 30 months (95% CI=15-45 months). In conclusion, the natural history of MCDK is usually benign but patients must have long-term follow-up with US scans and blood pressure measurements.

Nephrectomy for multicystic dysplastic kidney: if and when?

OBJECTIVES

To evaluate the criteria for conservative versus surgical treatment of multicystic dysplastic kidneys and to attempt to specify the optimal timing for surgery, when considered indicated.

METHODS

The study population comprised 48 antenatally or neonatally detected consecutive patients with unilateral multicystic dysplastic kidney. The fate of the affected renal conglomerate was regularly analyzed by ultrasonography. All cases were primarily followed up conservatively. In the patients who eventually underwent nephrectomy, the decision to operate was made after a minimum of 18 months (median 25).

RESULTS

Ultrasound follow-up showed complete involution in 13 cases (27%); in 35 cases (73%), the renal conglomerate persisted throughout the study period (mean 46 months). Of the 48 patients, 32 (67%) eventually underwent nephrectomy. The size of the affected mass among the involuted cases was significantly smaller throughout the study period than in those requiring nephrectomy. The difference between the two groups continuously increased during follow-up, with a mean involution rate of 2.5 cm/yr versus 0.6 cm/yr (up to 18 months) for the involuted versus noninvoluted cases, respectively (P <0.0001). From 18 months on, no statistically significant involution was observed in those who eventually underwent nephrectomy.

CONCLUSIONS

Patients with antenatally or neonatally detected multicystic dysplastic kidney can primarily be followed up conservatively. Involution occurs in approximately one fourth of the cases, usually within about 14 months. In our experience, no significant involution can be expected to occur after 18 months. If surgery is decided on, we recommend an age of about 2 years. Late complications (eg, Wilms' tumor and renovascular hypertension) are rare.

Unilateral multicystic dysplastic kidney: experience in children

OBJECTIVES

To report a retrospective study of unilateral multicystic dysplastic kidneys (MCDK) in children, assessing the contralateral kidneys and urinary tract, the functional consequences, and the urological and nephrological management and outcome, as unilateral MCDK is the most common cause of renal cystic disease in children, and malformations of the contralateral urinary tract and kidney (pelvi-ureteric obstruction, megaureter, reflux, renal dysplasia) have been reported.

PATIENTS AND METHODS

The study included 97 patients (60 boys, 37 girls) with MCDK seen between 1985 and 1998; 82 were diagnosed in utero by ultrasonography (US). After birth, the diagnosis was verified by US, renal scanning (in 93) or intravenous urography (in four), and 89 (92%) had voiding cysto-urethrography (VCUG). Of the 97 children, 87 (90% had a mean (range) follow-up of 44.3 (15-115) months.

RESULTS

The MCDK was removed in 17 children; the follow-up of 75 children (five lost to follow-up) showed total involution of the MCDK in 25%, shrinkage in 60% and a stable size in 15%. None had any sign of malignancy. The contralateral kidney showed anomalies in 19 of 97 children (20%); 12 had a dilated renal pelvis (two with megaureter), six had a high echogenicity of the contralateral kidney (one had reflux, and two also pelvic dilatation). In only four of the 89 children was reflux found by VCUG; 16 of the 19 anomalies were detected by US. Five children needed surgery on the contralateral urinary tract (three a pyeloplasty, and one each a pyeloplasty plus ureteroneocystostomy, and an antireflux procedure). Of the contralateral kidneys 43% showed compensatory hypertrophy. There was mild renal insufficiency in three children; renal function seemed to be slightly impaired in many. Five infants had hypertension (four with spontaneous resolution) caused by renal scarring after pyelonephritis or inborn dysplasia of the contralateral kidney. There were symptomatic urinary tract infections in seven children.

CONCLUSION

US can be used safely to diagnose unilateral MCDKs and malformations of the contralateral urinary tract and kidney. In cases where US of the dysplastic kidney remains uncertain renal scintigraphy is necessary to detect the lack of renal function. The low rate of reflux makes routine VCUG unnecessary if the contralateral upper urinary tract and kidney appear to be normal on US. Nephrectomy of the dysplastic kidney in typical cases is also unnecessary. A long-term nephro-urological follow-up of children with MCDK is recommended.

A 5-year audit of 778 neonatal renal scans (Part 2). Miscellaneous anomalies in 59 infants: A pictorial presentation

In this 5-year review of 778 neonatal renal scans seen in an obstetric hospital, Mercy Hospital for Women, Melbourne, most infants were referred because of antenatal ultrasound findings. Ninety-two percent of these had fetal pyelectasis. The results were classified on the ultrasound findings. The majority of neonates (76%) had a normal postnatal scan. A number had vesicoureteric reflux found on micturating cystourethrogram. Persisting mild/moderate pyelectasis or hydronephrosis (15%) proved to be a normal variant in many infants, but had a similar appearance to those with an early obstructive cause (1%). There were 59 infants (8%) with a miscellaneous group of renal anomalies, many with a characteristic antenatal ultrasound appearance suggesting the diagnosis. Review of these 59 infants illustrates the anomalies seen and reports the associated investigations and subsequent outcome in most cases.

Renal cystic neoplasms and renal neoplasms associated with cystic renal diseases: pathogenetic and molecular links

Cystic renal neoplasms represent an isolated cystic mass not accompanied by cystic change of the renal parenchyma. Although cystic change may be seen in any type of renal neoplasm, a few (i.e., cystic renal cell carcinoma, cystic nephroma, cystic partially differentiated nephroblastoma, mixed epithelial and stromal tumor) are characterized by constant cystic change that may involve the entire tumor. Cystic kidney disease is characterized by cystic change, which usually involves the kidneys in a bilateral and diffuse pattern, does not create a discreet mass, and is due to hereditary or developmental conditions. Some of the cystic kidney diseases are not known to give rise to renal neoplasm; others such as autosomal polycystic kidney disease or multicystic dysplastic kidney may fortuitously coexist with renal neoplasms. Three conditions (acquired cystic kidney disease, tuberous sclerosis, and von Hippel-Lindau disease) are associated with renal neoplasms with such a high frequency that they are considered preneoplastic. This article reviews the differential diagnoses among cystic neoplasms. It also focuses on the underlying genetic and molecular mechanisms for the relationship between cystic renal diseases and renal neoplasms.

A family study and the natural history of prenatally detected unilateral multicystic dysplastic kidney

PURPOSE

We document the inheritance pattern of multicystic dysplastic kidney in 3 affected families and screen first-degree relatives of a cohort of children with prenatally detected multicystic dysplastic kidney for renal anomalies. The study also afforded an opportunity to document the natural history of prenatally detected multicystic dysplastic kidney.

MATERIALS AND METHODS

We identified 3 families during clinical treatment of children with prenatally detected multicystic dysplastic kidneys. Other members of these families were evaluated with renal ultrasonography. For the family screening study index cases were identified from a fetal uropathy database. A total of 94 first-degree relatives (52 parents, 35 full siblings and 7 half siblings) of 29 children with prenatally detected multicystic dysplastic kidneys were studied with urinary tract ultrasonography, blood pressure measurement, urinalysis and plasma biochemistry.

RESULTS

Two families had affected sibling pairs, 1 of which also had a half sibling with vesicoureteral reflux. The third family included 3 individuals with multicystic dysplastic kidney and 1 with renal agenesis thought to have resulted from involution of multicystic dysplastic kidney. This family is consistent with autosomal dominant inheritance with variable expressivity and reduced penetrance. In the screening study ultrasonography did not demonstrate significant renal anomalies in any of the 94 first-degree relatives of the multicystic dysplastic kidney index cases. Followup assessment of prenatally detected multicystic dysplastic kidneys in index cases demonstrated total involution in 52% at a median age of 6.5 years with no multicystic dysplastic kidney related morbidity.

CONCLUSIONS

Multicystic dysplastic kidney can be familial but is most commonly a sporadic anomaly. Formal screening of relatives is not recommended. Followup data on a cohort of children with prenatally detected multicystic dysplastic kidney add further support to conservative management.

Prenatal diagnosis: does it alter outcome?

The prenatal detection of urinary tract anomalies is changing paediatric practice but in many areas the impact on clinical outcome remains difficult to quantify. However it is already apparent that termination of pregnancy has reduced the numbers of infants with lethal pulmonary hypoplasia and renal dysplasia who would previously have been liveborn but destined to succumb as neonates. Similarly, referrals of major non lethal abnormalities such as bladder exstrophy are declining as parents increasingly opt for termination. Fetuses at greatest risk of early onset postnatal renal failure can now be identified with considerable accuracy on prenatal ultrasound. Termination, prompted by quality of life considerations, could result in reduced numbers of infants and young children requiring end stage renal failure treatment in the first few years of life. Pre natal detection of anomalies such as PUJ obstruction and reflux undoubtedly provides an opportunity to avert functional deterioration and minimise urinary infection. But the proportion of children who genuinely benefit has proved difficult to assess. The prenatal detection of mild dilatation is of doubtful benefit in all but a minority of cases. Clinically significant underlying pathology is rare yet this common prenatal finding often generates disproportionate parental anxiety.

Clinicopathologic features of nephrogenic rests and nephroblastomatosis

Nephrogenic rests are the consequence of residual metanephric tissue in a fully developed kidney. They usually occur along the perimeter of a mature renal lobe (i.e., perilobar), within the lobe itself (i.e., intralobar), or both (i.e., combined). Nephrogenic rests can be grossly obvious or microscopically discrete. Nephroblastomatosis designates nephrogenic rests that are multifocal or diffuse, and implies more extensive disease. Universal (panlobar) nephroblastomatosis denotes complete replacement of the renal lobe by nephrogenic tissue. The fate of nephrogenic rests and nephroblastomatosis varies and includes obsolescence, sclerosis, dormancy, hyperplasia, or neoplasia. Evidence strongly suggests that neoplastic transformation of nephrogenic rests results in Wilms' tumor (nephroblastoma). Nephrogenic rests almost always occur in the setting of Wilms' tumor; perilobar rests show a strong association with synchronous bilateral Wilms' tumors, whereas intralobar rests are more strongly associated with metachronous tumors. Genetic studies have shown that nephrogenic rests often share many of the same chromosomal defects as Wilms' tumor, which provides further evidence that they are precursors to nephroblastoma. Thus, nephrogenic rests are recognized as clinically significant entities requiring adequate detection and close surveillance. Heightened awareness regarding the clinical relevance of nephrogenic rests and nephroblastomatosis (1) has led to improved detection of these precancerous lesions, (2) fostered more intensive investigation into their biologic behavior, and (3) initiated in-depth discussions about potentially new treatment regimens. The pathologists' ability to identify and detect nephrogenic rests has benefited from the more efficient Beckwith classification. Radiologists have deployed high-resolution radiologic/imaging modalities to improve detection of nephrogenic rests in situ. Clinicians and surgeons are more aware of the impact that nephrogenic rests have upon patient management. Despite this progress, more data is needed to further define these lesions.

Multicystic dysplastic kidney and Kallmann's syndrome: a new association?

BACKGROUND

Kallmann's syndrome is characterized by anosmia and hypogonadotrophic hypogonadism. Radiographic studies of teenagers and older subjects with the X-linked form of the syndrome have shown that up to 40% have an absent kidney unilaterally. Although this has been attributed to renal "agenesis", a condition in which the kidney fails to form, little is known about the appearance of the developing urinary tract either pre- or post-natally in individuals with Kallmann's syndrome.

METHODS

We describe two brothers who had features of Kallmann's syndrome, most probably of the X-linked variety, who both had a major urinary-tract malformation detected before birth.

RESULTS

The brothers were found to have unilateral multicystic dysplastic kidneys on routine antenatal ultrasound scanning and both underwent surgical nephrectomy of these organs post-natally. Immunohistochemical studies on the younger sibling revealed hyperproliferative dysplastic kidney tubules which overexpressed PAX2, a potentially oncogenic transcription factor, and BCL2, a cell-survival factor, surrounded by metaplastic, alpha smooth-muscle actin-positive stroma: similar patterns have been observed in patients with non-syndromic multicystic dysplastic kidneys.

CONCLUSIONS

Our results describe a new type of urinary-tract malformation associated with Kallmann's syndrome. However, since multicystic kidneys tend to involute, only when more Kallmann's syndrome patients are screened in utero or in early childhood using structural renal scans, will it be possible to establish whether multicystic kidney disease is a bona-fide part of the syndrome.

A molecular and genetic view of human renal and urinary tract malformations

Malformations of the kidney and lower urinary tract are common causes of chronic renal failure in infants and young children, but little is known about the molecular pathogenesis of these disorders. In animal experiments, the main causes of malformation are mutations, chemical and pharmaceutical teratogens, obstruction of fetal urinary flow, and alterations of maternal nutrition. The focus of this review is to consider how mutations and other alterations of gene expression during development cause human urinary tract malformations. Some of these disorders are associated with congenital anomalies in multiple organ systems, and two such syndromes are considered in detail: first, the renal-coloboma syndrome, in which mutations of the PAX2 transcription factor cause partial failure of urinary tract growth; second, Kallmann's syndrome, in which mutations of a cell-signaling molecule are associated with the absence of the urinary tract. In patients seen by nephrologists and urologists, however, most urinary tract malformations occur in isolation, and in some of these individuals, a genetic pathogenesis is strongly suggested by a positive family history and genetic linkage studies. One common example is primary vesicoureteric reflux. Furthermore, sporadic malformations have been shown to be associated with polymorphisms of genes expressed during construction of the urinary tract. In the long term, an understanding of the genetic aspects of human urinary tract malformations will help to unravel the pathogenesis of these disorders and may facilitate the design of genetic screening tests with a view to early diagnosis.

Outcome and cost analysis of operative versus nonoperative management of neonatal multicystic dysplastic kidneys

PURPOSE

We determine whether nephrectomy or observation is the more appropriate treatment of neonates with multicystic dysplastic kidney in terms of medical care and cost-effectiveness.

MATERIALS AND METHODS

We retrospectively reviewed our 10-year clinical experience with 17 female and 32 male neonates presenting with multicystic dysplastic kidney who were followed with serial renal ultrasound. The literature also was reviewed.

RESULTS

Nephrectomy was performed in 12 patients (24%) for various reasons, of which family request at concomitant surgery was the most common (7). No kidney was removed due to hypertension or tumor. In the remaining 37 patients followup continues (mean 42 months) with involution developing in 9 multicystic dysplastic kidneys (24%) and 9 patients (24%) lost to followup. The total cost of 1-hour outpatient simple nephrectomy was estimated at $5,000 to $7,000 and, when performed as a concomitant procedure, it cost $2,000 to $5,000, the equivalent charges incurred for 17 to 28 serial ultrasound studies performed by a radiologist. Our review of the literature revealed that children with multicystic dysplastic kidney are at minimal risk for hypertension, pain and infection. The most important reason to perform screening renal ultrasound in this condition is to detect earlier stage Wilms tumor (3 to 10-fold the general pediatric population risk of 1/10,000 cases). With a maximum risk of 0.1% for Wilms tumor controversy exists as to whether any screening program is necessary. When screening is instituted, options include monthly parental abdominal palpation versus serial renal ultrasound. Because Wilms tumor has a rapid growth rate, when screening renal ultrasound is instituted, it must be performed no less than every 3 months until age 8 years (total of 32 studies) to screen effectively for early stage tumors.

CONCLUSIONS

The risks associated with multicystic dysplastic kidney are slight. Early nephrectomy is more cost-effective than observation in neonates with multicystic dysplastic kidney only when observation involves screening with ultrasonography every 3 months until age 8 years. Extensive parental counseling should be provided on the slight but definite risks of this condition.