Unilateral multicystic dysplastic kidney: long term outcomes

Clinical Characteristics and Outcomes of Children with Unilateral Multicystic Dysplastic Kidney: A Cohort Study

OBJECTIVES

To study the clinical profile and outcomes of children with unilateral multicystic dysplastic kidney (MCDK).

METHODS

We assessed the clinical features and extrarenal manifestations in children with unilateral MCDK. These children were followed up to ascertain involution, compensatory hypertrophy and progression of chronic kidney disease (CKD) stage.

RESULTS

We enrolled 106 children with unilateral MCDK which was detected antenatally in 98 (92.4%), while evaluating for urinary tract infection in three (2.8%), and incidentally in five (4.7%) children. Abnormalities in the contralateral kidney and extrarenal manifestations at initial presentation were detected in 30 (28.3%) and 15 (14.2%), respectively. At a median (IQR) follow-up of 60 (32, 87) months, 34 (32.1%) children demonstrated complete involution of the MCDK, while 72 (67.9%) showed compensatory hypertrophy in the contralateral kidney. The median age at involution of MCDK was 48.5 (33, 86.5) months. Twenty-two (20.7%) children had non-regression of MCDK, and two (1.9%) underwent nephrectomy. Eight (7.5%) children developed hypertension and two children were detected to have proteinuria. One child, each, progressed to CKD stage 2 and stage 3a; and another child (0.9%) progressed to end stage kidney disease. None of the patients developed malignant transformation.

CONCLUSIONS

Majority of cases (92.4%) of MCDK had been detected antenatally. The rate of involution was 32.1% at a median follow-up of 60 months. Although, 28.3% of cases of MCDK had abnormalities in the contralateral kidney, progression of CKD to a higher stage occurred only in three (2.8%) cases.

Early diagnosis of solitary functioning kidney: comparing the prognosis of kidney agenesis and multicystic dysplastic kidney

BACKGROUND

Individuals with congenital solitary functioning kidney (SFK) are at an increased risk of kidney damage. According to some studies, the risk is higher in unilateral kidney agenesis (UKA) than in unilateral multicystic dysplastic kidney (UMCDK). We hypothesized that with early detection of children with UKA and UMCDK, there would be no difference in the presence of hypertension, proteinuria, and reduced glomerular filtration rate (GFR) between UKA and UMCDK.

METHODS

Based on a long-term follow-up protocol, we evaluated a cohort of 160 children followed from birth for SFK (84 with UKA and 76 with UMCDK) detected by prenatal or routine neonatal ultrasound screening. Hypertension, proteinuria, and reduced GFR were monitored as markers of kidney damage. We compared the characteristics and outcomes of the subgroups of children with UKA and UMCDK.

RESULTS

GFR was reduced in 42 (26.2%) children, of whom 41 showed only mild reduction. Hypertension and proteinuria were found in 22 (13.8%) and 14 (8.8%) children, respectively. Combined kidney damage was present in 57 (35.6%) children. The UMCDK and UKA subgroups differed in GFR at final examination, with UMCDK patients being significantly more likely to have normal GFR compared to UKA patients (82% vs. 67%; p = 0.039).

CONCLUSIONS

One third of the children showed signs of SFK damage, albeit mild. Patients with UKA had reduced GFR significantly more often than those with UMCDK, but did not differ in the rates of hyperfiltration injury or congenital anomalies of the kidneys and urinary tract (CAKUT) in SFK.

Multicystic renal dysplasia, a histomorphological spectrum: Seven years experience from a tertiary care hospital

OBJECTIVES

Multicystic dysplastic kidney (MCDK) is defined as the presence of multiple noncommunicating cysts of various sizes, detected sonographically, without evidence of functioning renal parenchyma on dimercaptosuccinic acid renal scan. It has an incidence of 1:4000 live births. They are more commonly diagnosed in boys, usually on the left side, but may also be bilateral. There is the presence of primitive ducts surrounded by fibromuscular connective tissue. These are because of the disturbed connection of the ureteric bud with renal blastema and abnormal division at the stage of metanephros, resulting in an abnormal metanephros differentiation.

MATERIALS AND METHODS

Thirty cases of MCDK were included to study their histomorphology along with their clinical features. Cases were retrieved from the last seven years (2015-2021) from the Department of Pathology, Maulana Azad Medical College.

RESULT

Age ranged from 10 days to 18 years. The cases were between 1 years and 5 years of age. Six out of 30 cases (20%) were infants with three of them being neonates. Twenty-one cases were males. All the cases had unilateral kidney involvement with the left kidney being involved in 20 out of 30 cases. Twenty-eight cases underwent nephrectomy in view of small contracted nonfunctional kidneys with one of them being horseshoe shaped. Five cases had associated hydronephrosis (two ipsilateral and three bilateral). One case had Hirshprung's disease, four had anorectal malformation, two had posterior urethral valves with vesicourethral reflux, one had duplex moiety, and one had undescended testes. On histopathological examination, all of them showed the presence of immature disorganized tubules surrounded by a collarette of immature mesenchymal stroma. One of the cases showed osteoid formation and four had areas of immature cartilage. Normal kidney parenchyma was seen at the periphery in four cases.

CONCLUSION

This series has been presented to highlight the various histomorphological features of MCDK. MCDK can be managed conservatively in most of cases due to autoinvolution and, hence, needs to be differentiated from other close differentials like polycystic kidney disease, cystic nephroma, and cystic partially differentiated nephroblastoma in order to avoid unnecessary surgical intervention.

Predicting outcomes in children with congenital anomalies of the kidney and urinary tract

BACKGROUND

Congenital anomalies of the kidney and urinary tract (CAKUT) are the most frequent causes of childhood chronic kidney disease (CKD). Using a large CAKUT cohort, we sought to identify the predictors of CKD and to develop a prediction model that informs a risk-stratified clinical pathway.

METHODS

This was a retrospective cohort study including cases with multicystic dysplastic kidneys (MCDK), unilateral kidney agenesis (UKA), kidney hypoplasia (KH), and posterior urethral valves (PUV). We identified risk factors for CKD (estimated glomerular filtration rate [eGFR] <60 ml/min/1.73 m2) and tested their performance in an adjusted multivariate binary regression model. Prediction probability scores for CKD were used to separate cases likely to develop complications from those not needing specialist follow-up.

RESULTS

We identified 452 eligible cases of CAKUT with 22% developing CKD. Strongest associations with CKD included primary diagnosis (OR 3.5, 95% CI 2.6-4.6), preterm delivery (OR 2.3, 95% CI 1.2-4.4), non-kidney anomalies (OR 1.8, 95% CI 1.1-3), first eGFR<90 (OR 8.9, 95% CI 4.4-18.1), small kidney size (OR 9, 95% CI 4.9-16.6), and additional kidney anomalies (OR 1.6, 95% CI 1.2-2.8). PUV (OR 4.7, 95% CI 1.5-15.3), first eGFR <90 (OR 4.4, 95% CI 2-9.7), and kidney length to body length ratio <7.9 (OR 4.2, 95% CI 1.9-9.2) were independent predictors of CKD. The regression model had a prediction accuracy of 80% and a prediction probability c-statistic of 0.81.

CONCLUSION

Using a large combined CAKUT cohort we identified risk factors for CKD. Our prediction model provides the first steps towards a risk-stratified clinical pathway. A higher resolution version of the Graphical abstract is available as Supplementary information.

Classifying and evaluating fetuses with multicystic dysplastic kidney in etiologic studies

Multicystic dysplastic kidney (MCDK) is one of the most common fetal malformations, but its etiology remains unclear. Identification of the molecular etiology could provide a basis for prenatal diagnosis, consultation, and prognosis evaluation for MCDK fetuses. We used chromosome microarray analysis (CMA) and whole-exome sequencing (WES) to conduct genetic tests on MCDK fetuses and explore their genetic etiology. A total of 108 MCDK fetuses with or without other extrarenal abnormalities were selected. Karyotype analysis of 108 MCDK fetuses showed an abnormal karyotype in 4 (3.7%, 4/108) of the fetuses. However, CMA detected 15 abnormal copy number variations (CNVs) (14 pathogenic CNVs, and one variant of unknown significance [VUS] CNVs), in addition to four cases that were consistent with the results of karyotype analysis. Out of the 14 pathogenic CNVs cases, three were of 17q12 microdeletion, two of 22q11.21 microdeletion, 22q11.21 microduplication uniparental disomy (UPD), and one case of 4q31.3q32.2 microdeletion, 7q11.23 microduplication, 15q11.2 microdeletion, 16p11.2 microdeletion, and 17p12 microdeletion. Of the 89 MCDK fetuses with normal karyotype analysis and CMA, 15 were tested by WES. Two (13.3%, 2/15) fetuses were identified by WES as Bardet-Biedl syndrome (BBS) 1 and BBS2. Combined application of CMA-WES to detect MCDK fetuses can significantly improve the detection rate of genetic etiology, providing a basis for consultation, and prognosis evaluation.

[Developmental abnormalities of the kidney]

Les anomalies du développement rénal sont fréquentes chez le fœtus et correspondent à un défaut des étapes de la néphrogenèse. La plupart d’entre elles ont une évolution favorable, mais la gravité potentielle de certaines malformations rend leur dépistage et leur prise en charge précoce essentiels. Le dépistage de ces anomalies repose sur l’échographie fœtale. L’échographie devra préciser le pronostic de l’anomalie en recherchant des critères de gravité, tels qu’une atteinte rénale bilatérale, une altération de la quantité de liquide amniotique, témoin d’une altération de la fonction rénale fœtale, ou encore l’existence d’atteintes extra-rénales associées. Dans les cas les plus sévères, une prise en charge dans un centre pluridisciplinaire de diagnostic prénatal (CPDPN) est indispensable. Les anomalies du développement rénal peuvent être isolées ou s’inscrire dans le cadre d’un syndrome poly-malformatif. L’apport de la génétique dans la compréhension de ces anomalies est d’une aide considérable.

WT1 regulates expression of DNA repair gene Neil3 during nephrogenesis

Mammalian nephrons arise from a population of nephron progenitor cells (NPCs) expressing the master transcription factor Wilms tumor-1 (WT1), which is crucial for NPC proliferation, migration, and differentiation. In humans, biallelic loss of WT1 precludes nephrogenesis and leads to the formation of Wilms tumor precursor lesions. We hypothesize that WT1 normally primes the NPC for nephrogenesis by inducing expression of NPC-specific DNA repair genes that protect the genome. We analyzed transcript levels for a panel of DNA repair genes in embryonic day 17.5 (E17.5) versus adult mouse kidneys and noted seven genes that were increased >20-fold. We then isolated Cited1⁺ NPCs from E17.5 kidneys and found that only one gene, nei-like DNA glycosylase 3 (Neil3), was enriched. RNAscope in situ hybridization of E17.5 mouse kidneys showed increased Neil3 expression in the nephrogenic zone versus mature nephron structures. To determine whether Neil3 expression is WT1 dependent, we knocked down Wt1 in Cited1⁺ NPCs (60% knockdown efficiency) and noted a 58% reduction in Neil3 transcript levels. We showed that WT1 interacts with the Neil3 promoter and that activity of a Neil3 promoter-reporter vector was increased twofold in WT1⁺ versus WT1^- cells. We propose that Neil3 is a WT1-dependent DNA repair gene expressed at high levels in Cited1⁺ NPCs, where it repairs mutational injury to the genome during nephrogenesis. NEIL3 is likely just one of many such lineage-specific repair mechanisms that respond to genomic injury during kidney development.NEW & NOTEWORTHY We studied the molecular events leading to Wilms tumors as a model for the repair of genomic injury. Specifically, we showed that WT1 activates DNA repair gene Neil3 in nephron progenitor cells. However, our observations offer a much broader principle, demonstrating that the embryonic kidney invests in lineage-specific expression of DNA repair enzymes. Thus, it is conceivable that failure of these mechanisms could lead to a variety of "sporadic" congenital renal malformations and human disease.

Antenatally Diagnosed Kidney Anomalies

Congenital anomalies of the kidney and urinary tract encompass a broad spectrum of developmental conditions that together account for the majority of childhood chronic kidney diseases. Kidney abnormalities are the most commonly diagnosed congenital anomaly in children, and detection of this anomaly is increasing as a result of improved antenatal care and widespread access to more sensitive screening ultrasonography. Most paediatricians will encounter children with congenital kidney anomalies across a wide spectrum of disorders, and a broad understanding of the classification, investigation, and basis of management is important to appropriately direct their care.

Outcomes of solitary functioning kidneys-renal agenesis is different than multicystic dysplastic kidney disease

BACKGROUND

Multicystic dysplastic kidney (MCDK) disease and unilateral renal agenesis (URA) are well-known causes of a solitary functioning kidney (SFK) and are associated with long-term kidney injury. The aims of this study were to characterize the natural history of SFK at our center, define the risk factors associated with chronic kidney injury, and identify distinguishing features between URA and MCDK that predict outcome.

METHODS

This was a retrospective cohort study of 230 SFK patients. We compared MCDK (n=160) and URA (n=70) according to clinical features at diagnosis and kidney outcomes over follow-up. Univariate and multivariate binary regression analysis was used to determine independent risk factors for chronic kidney injury, defined as the composite outcome of hypertension, proteinuria, or chronic kidney disease (eGFR <60 mL/min/1.73m²).

RESULTS

URA had a higher prevalence of comorbid genetic syndromes (15 vs. 6%, p=0.04), non-renal anomalies (39 vs. 11%, p<0.001), and congenital anomalies of the kidney and urinary tract (CAKUT) (51 vs. 26%, p<0.001) than MCDK. Over follow-up, URA experienced more hypertension (19 vs. 3%, p=0.002), proteinuria (12 vs. 3%, p=0.03), and the composite outcome (19 vs. 6%, p=0.003) than MCDK. Independent risk factors for chronic kidney injury included CAKUT (OR 5.01, p=0.002) and URA (OR 2.71, p=0.04).

CONCLUSIONS

In our population, URA was more likely to have associated syndromes or anomalies, and to have worse outcomes over time than MCDK. URA diagnosis was an independent risk factor for chronic kidney injury. Our results will be used to develop a standardized clinical pathway for SFK management. A higher resolution version of the Graphical abstract is available as Supplementary information.

Reverse Phenotyping Maternal Cystic Kidney Disease by Diagnosis in a Newborn: Case Report and Literature Review on Neonatal Cystic Kidney Diseases

Summary. Kidney cysts are the most common kidney lesion, while congenital kidney cysts are mostly found in pediatric population. Neonatal kidney cysts can develop due to fetal malformations, rare genetic disorders or can be acquired which is very rare. Kidney cysts may be the only isolated finding or be part of the overall phenotype. They can be asymptomatic, found by ultrasound accidentally or can manifest from mild to life-threatening symptoms. Therefore, early diagnosis is very important. Autosomal dominant polycystic kidney disease and autosomal recessive polycystic kidney disease are the most common causes of kidney cysts in the neonatal population. This review highlights the most common kidney cystic diseases during the neonatal period and a rare clinical case of HNF1B-associated disease.

Reducing Unnecessary Imaging in Children With Multicystic Dysplastic Kidney or Solitary Kidney

BACKGROUND AND OBJECTIVES

Children with isolated unilateral multicystic dysplastic kidney (MCDK) or congenital solitary kidney (CSK) undergo serial renal ultrasonography with variable frequency until they are transitioned to adult care. A growing body of literature suggests the value of frequent ultrasonography in this population is limited, providing no benefit to overall outcomes. Despite emerging evidence, ultrasound remains overused, resulting in avoidable health care expenditures and unnecessary use of resources. With our initiative, we aimed to improve quality of care by reducing avoidable ultrasounds in these children.

METHODS

This was a single-center, prospective, interrupted time series of children <18 years with ultrasound-confirmed isolated unilateral MCDK or CSK in the outpatient nephrology clinic to evaluate the effect of a decision-making algorithm on the proportion of children receiving an avoidable ultrasound. An algorithm depicting a consensus, evidence-based protocol for managing pediatric MCDK or CSK was refined through content expert feedback and usability testing to standardize frequency of ultrasonography. Ultrasounds were deemed necessary after birth, at 6 months, and at 2, 5, 10, and 15 years. Differences pre- and postintervention were determined by using a U chart and t and F tests for significance.

RESULTS

The algorithm resulted in a 47% reduction (P < .001) in the proportion of avoidable ultrasounds ordered in children with MCDK and CSK. This reduction was sustainable over a 6-month period and would result in at least $46 000 annual savings.

CONCLUSIONS

Introduction of a clinical decision-making algorithm was associated with a reduction in avoidable ultrasound testing. Improving adherence across providers may allow for an even more pronounced reduction.

Renal function in children with a congenital solitary functioning kidney: A systematic review

INTRODUCTION

Abnormal renal development that results in lack of function or development of one of two kidneys is known as congenital solitary functioning kidney (CSFK). Two well characterized sub-categories of CFSK are unilateral renal agenesis (URA) and multicystic dysplastic kidney (MCDK). This systematic review sought to evaluate the change in renal function in children ≤18 years old with a CSFK as a result of URA or MCDK.

METHODS

A literature search in MEDLINE and Embase was conducted (1946 to July 13, 2020). All relevant articles were retrieved and evaluated based on pre-selected criteria by two independent researchers. Data was then extracted from variables of interest and conflicts were resolved by a third researcher. The primary outcome was renal function, and the secondary outcomes were proteinuria and hypertension.

RESULTS

Forty-five studies were included, of which 49% (n = 22) were retrospective and/or 58% (n = 26) were cohort studies. A combined total of 2148 and 885 patients were diagnosed with MCDK or URA, respectively. The proportion of children with worsened renal function at follow-up was found to be 8.4% (95% CI: 5.2%-13.4%). Among the studies reporting renal function as a group mean or median at follow-up, 84% (21/25) had a GFR/CrCl above 90 (mL/min/1.73  m²/ml/min). In terms of secondary outcomes, the proportion of children with proteinuria and hypertension was found to be 10.1% (95% CI: 6.9%-14.6%) and 7.4% (95% CI: 5.0%-10.9%), respectively.

CONCLUSION

The risk of developing proteinuria (10.1%), hypertension (7.4%), and/or worsened renal function (8.4%) for children with CFSK as a result of MCDK or URA is low. However, the level of evidence in the literature is weak. Further research is needed to identify the predisposing factors that may differentiate the small subset of children with CSFK at a higher risk of developing adverse renal outcomes.

Retrospective evaluation of the pediatric multicystic dysplastic kidney patients: experience of two centers from southeastern Turkey

Background/aim

The objective of this study is to determine the clinical features of unilateral multicystic dysplastic kidney (MCDK) patients.

Materials and methods

The demographic, clinical, laboratory, and radiologic features of MCDK patients at Diyarbakır Children’s Hospital and Diyarbakır Gazi Yaşargil Training and Research Hospital between January 2008-June 2019 were retrospectively evaluated.

Results

A total of 111 [59 (53.2%) male and 52(46.8%) female] patients with MCDK were followed for a mean period of 41.89 ± 32.03 months. MCDK was located on the left and right sides in 46 (41.4%) and 65 (58.6%) of the children, respectively (p > 0.05). A total of 87 (78.4%) patients had antenatal diagnosis. The mean age at diagnosis was 13.7 ± 34.2 months. Of the 49 voiding cystourethrogram (VCUG)-performed patients, vesicoureteral reflux was detected in 11 patients (22.4%). Other associated urological anomalies in the patients were detected in 12 (10.8%) patients. On Tc-99m dimercaptosuccinic acid (DMSA) scintigraphy which was performed in all patients showed scarring in four children. Eight patients had history of UTI (7.2%). Renal failure, hypertension, and proteinuria were diagnosed in three children (2.7%). Sixty-nine (62%) patients developed compensatory hypertrophy.

Conclusion

All cases should be followed up closely and VCUG should be reserved for patients with recurrent UTI and other urological problems indicated by ultrasonography and abnormal DMSA scan results.

Posterior Urethral Valve and Prenataly Resolved Multicystic Dysplastic Kidney

Multicystic dysplastic kidney is a rare congenital anomaly of the kidney and urinary tract. The association with the posterior urethral valve is also very rare. Here we present a patient with both entities and prenatal resolution of the cysts.A 10-week old baby was referred for nephrourological work up due to prenatal diagnosis of the left multicystic kidney. He had serial US scans during the pregnancy. Immediately before delivery the cysts were not seen (prenatal resolution). There were no extrarenal anomalies. The first postnatal ultrasound scan revealed normal sized right kidney without dilatation of the pelvicalyceal system. The bladder had normal thickness of the wall. Technetium-99m dimercaptosuccinic acid scan showed no activity on the left side, and the right kidney appeared normal. At two months of age, a poor urinary steam was observed and additional urologic work up was indicated on clinical suspicion of PUV. Voiding urethrocystography revealed posterior urethral valve and the baby underwent cytoscopic valve resection.Conclusion: We present a rare association of two congenital anomalies of the kidney and urinary tract with prenatal involution of the multicystic dysplastic kidney that is extremely rare event as seen in our case. Presence of posterior urethral valve must be suspected in a male baby with a poor urinary stream even when his ultrasound scan of urinary system appears normal.

Pathophysiological clinical features of an infant with hypertension secondary to multicystic dysplastic kidney: a case report

BACKGROUND

The association of hypertension with congenital renal hypoplasia has been established. We report a case of an infant who underwent nephrectomy for hypertension.

CASE PRESENTATION

Magnetic resonance imaging for the mother revealed fetal renal masses, and fetal multicystic dysplastic kidney was suspected. Following birth, the baby developed hypertension. Numerous investigations revealed that the left kidney was non-functional, and she was initiated on benazepril hydrochloride. However, because the drug response was poor, the left kidney was removed at the age of 7 months. Examination of the renal specimen revealed abrupt transition from normal to atrophic cortex with lobar atrophy and cysts. Tubular atrophy, marked abnormal blood vessels with wall thickening, gathered immature glomeruli, and parenchymal destruction were observed. Renin was partially localized in the proximal tubules and the parietal epithelium of the Bowman's capsule in the immature glomeruli. We speculated that an abnormal vascular structure and irregular renin localizations may be the cause of hypertension. Serum renin and aldosterone levels gradually reduced post-surgery, reaching normal levels on the 90th postoperative day. A long follow-up is needed due to the possibility of the child developing hypertension in the future.

CONCLUSION

This is a case of an infant with MCDK, which discusses the clinicopathological features based on the pathophysiological analysis, including renin evaluation.

Multicystic dysplastic kidney - treat each case on its merits

OBJECTIVES

To assess outcomes of unilateral multicystic dysplastic kidney (MCDK) managed at an Australasian centre over a 15 year period. To assess if MCDK involution could be predicted based on change noted between first two postnatal ultrasound scans 6 months apart.

SUBJECTS AND METHODS

A retrospective study was performed.

RESULTS

One-hundred-and-six cases of unilateral MCDK were studied. Eighty-four of these presented antenatally. Twenty-two MCDK cases presented postnatally. Urological anomalies associated with MCDK included vesicoureteric reflux (VUR), ureterocele and contralateral pelviureteric junction obstruction (PUJO). Children undergoing surgical intervention for these anomalies were offered concurrent MCDK nephrectomy. Morbidity associated with MCDK under surveillance included febrile culture-positive urinary tract infection in 20 cases (20.7%), hypertension in four (3.7%) and Wilms' tumor in one (0.9%). Thirty-six cases (34%) underwent complete involution, 32 (30.2%) were in the process of involuting and 38 cases (35.8%) underwent nephrectomy because of failure of involution or associated morbidity. If the MCDK reduced in cranio-caudal interpolar length by 20% or more between the first postnatal USS and the next one 6 months later, then it was very likely to involute spontaneously. If the MCDK did not reduce in cranio-caudal interpolar length by 20% between the first postnatal scan and the next one 6 months later, then it was highly likely to fail to involute, and in our study, correlated with the outcome of nephrectomy.

CONCLUSION

Although MCDK is a benign condition, it should be carefully investigated and followed-up, as involution may not occur in over a third. In some cases, morbidity may occur. Each case of MCDK should be managed on its own merits.

LEVEL OF EVIDENCE

Level II - Prognosis study, Retrospective.

Voiding Cystourethrogram in Children With Unilateral Multicystic Dysplastic Kidney: Is It Still necessary?

OBJECTIVE

To evaluate the value of the voiding cystourethrogram (VCUG) in children with multicystic dysplastic kidney (MCDK) who have a normal versus abnormal contralateral kidney and bladder ultrasound (US), and assess the risk of having vesicoureteral reflux (VUR) or urinary tract infection (UTI) based on the US results.

METHODS

A retrospective chart review including children with unilateral MCDK with postnatal US and VCUG available at our institution between January 2008 and September 2017 was performed. Analysis was done to find association between abnormal contralateral US and contralateral VUR and UTI.

RESULTS

One hundred and fifty-six children were analyzed; 118(75.6%) patients had a normal contralateral kidney US, while 38(24.4%) had abnormal US. The rate of severe contralateral VUR (grade IV and V) was 2 (1.7%) and 5 (13.2%) in children with normal and abnormal contralateral US, respectively. The risk analysis demonstrated a significant association between severe VUR on the contralateral kidney and an abnormal contralateral US (odds ratio = 7.73; 95%CI: 1.43-41.81; P = 0.018) and no significant association with UTI (odds ratio = 1.58; 95%CI: 0.50-4.94; P = 0.435).

CONCLUSION

Our data suggests, the rate of severe contralateral VUR in children with unilateral MCDK and normal contralateral kidney is low. VCUG should be considered for infants with proven MCKD and alterations on the contralateral kidney on US. Following patients with MCDK and normal contralateral kidney without the use of VCUG is a reasonable approach, unless there is development of signs and symptoms of recurrent UTI or deterioration of the renal function. We found that abnormal contralateral kidney US was associated with severe VUR.

Towards adulthood with a solitary kidney

Around 1/1000 people have a solitary kidney. Congenital conditions mainly include multicystic dysplastic kidney and unilateral renal aplasia/agenesis; acquired conditions are secondary to nephrectomy performed because of urologic structural abnormalities, severe parenchymal infection, renal trauma, and renal or pararenal tumors. Children born with congenital solitary kidney have a better long-term glomerular filtration rate than those with solitary kidney secondary to nephrectomy later in life. Acute and chronic adaptation processes lead to hyperfiltration followed by fibrosis in the remnant kidney, with further risk of albuminuria, arterial hypertension, and impaired renal function. Protective measures rely on non-pharmacological renoprotection (controlled protein and sodium intake, avoidance/limitation of nephrotoxic agents, keeping normal body mass index, and limitation of tobacco exposure). Lifelong monitoring should include blood pressure and albuminuria assessment, completed by glomerular filtration rate (GFR) estimation in case of abnormal values. In the absence of additional risk factors to solitary kidney, such assessment can be proposed every 5 years. There is no current consensus for indication and timing of pharmacological intervention.

Prenatal presentation of a rare genetic disorder: a clinical, autopsy and molecular correlation

Walker Warburg syndrome (WWS) lies at the severe end of the spectrum of the congenital muscular dystrophies. WWS is a congenital disorder of the O-glycosylation that disrupts in the post-translation modification of dystroglycan proteins. WWS is characterized by the involvement of the central nervous system and rarely by multisystem involvement. Next-generation sequencing discovered that multiple genes are associated with this disorder. FKTN is the rarest cause of WWS. We describe a clinical-autopsy report of a molecularly- confirmed WWS case presenting with ventriculomegaly, agenesis of the corpus callosum with a novel phenotype of Dandy-Walker malformation and unilateral multi-cystic kidney. The whole-exome sequencing confirmed a homozygous variant (c.411C>A) in the FKTN gene with a premature termination codon. This case emphasizes the importance of detailed postnatal phenotyping through an autopsy in any pregnancy with antenatally identified malformations. Obstetricians, pediatricians as well as fetal medicine experts need to counsel the parents and focus on preserving the appropriate sample for genetic testing. WWS, though rare deserves testing especially in the presence of positive family history. Dandy-Walker malformation is a novel feature and expands the phenotypic spectrum.

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.

The Incidence and Durability of Compensatory Hypertrophy in Pediatric Patients with Solitary Kidneys

OBJECTIVE

To evaluate the incidence and durability of compensatory hypertrophy with solitary kidneys in the setting of those with multicystic dysplastic kidney (MCDK) or Wilms tumor (WT) status postnephrectomy.

PATIENTS AND METHODS

We conducted a retrospective cohort study of patients with MCDK and WT. MCDK patients were verified by sonographic findings prenatally. WT patients entered our study at time of nephrectomy. We compared the natural history of hypertrophy between the 2 cohorts via renal length measurement. We performed linear regression to predict creatinine clearance from renal length after adjusting for age and cohort status (MCDK versus WT).

RESULTS

Fifty-two patients (56%) were diagnosed with WT, and 71 patients (44%) with MCDK patients met study criteria with a median age of postnatal ultrasound at 1.6 months (interquartile range 0.5-3.6). The median (IQR) follow-up time was 7.5 years. At the time of nephrectomy, 25/52 (48%) of Wilms patients had contralateral hypertrophy, while at diagnosis 22/71 (31%) of MCDK patients had contralateral hypertrophy, P = .03. Contralateral hypertrophy was a consistent finding throughout follow-up. As renal length increases by 1 cm, glomerular filtration rate increased by 7.8 mL/min/m² (95% confidence interval 1.8-13.8, P = .01).

CONCLUSION

Contralateral hypertrophy appears to be a compensatory mechanism for unilateral kidney pathology as demonstrated by MCDK and WT patients. Hypertrophy often occurs at the time of diagnosis and appears to be a permanent finding as children reach their teenage years. Additionally, in nonhydronephrotic kidneys, increases in renal length correlate with improvement in glomerular filtration rate. Overall, the majority of children with solitary kidneys demonstrate compensatory hypertrophy.

A meta-analysis of the incidence and fate of contralateral vesicoureteral reflux in unilateral multicystic dysplastic kidney

INTRODUCTION

Multicystic dysplastic kidney (MCDK) is the most common type of renal cystic disease. It is associated with urinary tract abnormalities in the contralateral kidney in up to 30% of cases, most commonly vesicoureteral reflux (VUR).

OBJECTIVES

The objective of this study was to describe the incidence and selected issues in management and evolution for each VUR grade in the contralateral kidney of patients with unilateral MCDK, in order to strengthen the scientific basis regarding the need for voiding cystourethrography (VCUG) screening.

METHODS

A comprehensive search of standard and gray literature was performed. Full-text screening, data abstraction, and quality appraisal were conducted in duplicates. Included studies reported a primary diagnosis of unilateral MCDK with contralateral VUR determined by VCUG. Articles had to include a distribution of VUR grade to meet the eligibility criteria.

RESULTS

From 698 retrieved articles, 37 studies enrolling 2057 patients were analyzed. Of the patients, 80% were male; 50% had left unilateral MCDK; and 87% were diagnosed prenatally. A total of 1800 patients had VCUG, of whom 303 had VUR (weighted proportion: 17%; 95% confidence interval [CI]: 14-20%). Weighted proportions of VUR were 9%, 7%, and 17% for grades I-II, III-V, and I-V, respectively. Of the patients, 99% (95% CI: 97-100%) were on continuous antibiotic prophylaxis (CAP) and 18% (95% CI: 8-37%) had urinary tract infections (UTIs), with a higher rate of UTIs (23% vs 10%) in patients with dilating (grades III-V) VUR, over a mean follow-up of 40 months. In patients with dilating VUR, reflux resolved or downgraded to grade I in 52% (95% CI: 37-67%) of patients, and 32% (95% CI: 19-49%) had surgical correction of VUR.

CONCLUSIONS

Among patients with unilateral MCDK, 17% have VUR in the contralateral kidney, 41% of which is dilating VUR. Of the cases with dilating VUR, half will resolve or downgrade to grade I during follow-up; 23% will develop a UTI despite CAP; and one-third will undergo ureteral re-implantation. While many physicians may thus choose to forego routine VCUG screening of the single functional kidney, shared decision-making with the patient's caregivers is currently recommended, where the risks and benefits of the different approaches can be discussed. The data from this analysis can help inform the discussions.

Imaging of Kidney Cysts and Cystic Kidney Diseases in Children: An International Working Group Consensus Statement

Kidney cysts can manifest as focal disease (simple and complex kidney cysts), affect a whole kidney (eg, multicystic dysplastic kidney or cystic dysplasia), or manifest as bilateral cystic disease (eg, autosomal recessive polycystic kidney disease [ARPKD] or autosomal dominant polycystic kidney disease [ADPKD]). In children, as opposed to adults, a larger proportion of kidney cysts are due to genetic diseases (eg, HNF1B nephropathy, various ciliopathies, and tuberous sclerosis complex), and fewer patients have simple cysts or acquired cystic kidney disease. The purpose of this consensus statement is to provide clinical guidance on standardization of imaging tests to evaluate kidney cysts in children. A committee of international experts in pediatric nephrology, pediatric radiology, pediatric US, and adult nephrology prepared systematic literature reviews and formulated recommendations at a consensus meeting. The final statement was endorsed by the European Society of Pediatric Radiology, the European Federation of Societies for Ultrasound in Medicine and Biology, the European Society of Pediatric Nephrology, and reviewed by the European Reference Network for Rare Kidney Diseases. Main recommendations are as follows: US is the method of choice when assessing pediatric kidney cysts, with selected indications for MRI and contrast-enhanced US. CT should be avoided whenever possible because of ionizing radiation. Renal US yields essential diagnostic information in many cases. In patients with ARPKD or other ciliopathies, abdominal US is needed for diagnosis and screening of portal hypertension. US is usually sufficient for follow-up kidney imaging, but MRI can be valuable for clinical trials in patients with ADPKD or in older children with tuberous sclerosis complex to evaluate both kidney cysts and angiomyolipomas.

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.

Clinical features of children with multicystic dysplastic kidney

BACKGROUND

To evaluate the clinical features of patients with multicystic dysplastic kidney (MCDK).

METHODS

The medical files of children diagnosed with MCDK between January 2008 and November 2015 were retrospectively reviewed. The demographic, clinical, laboratory and radiological data were evaluated.

RESULTS

Of 128 children with MCDK enrolled in the study, 82 (64.1%) were male, and 46 (35.9%) were female (P < 0.05). MCDK were located on left and right sides in 66 (51.6%) and 62 children (48.4%), respectively (P > 0.05). Antenatal diagnosis was present in 64 patients (50%). The mean age at diagnosis was 2.8 ± 2.7 years (range, 0-8 years), and follow-up duration was 4.5 years. Fifteen patients (20.8%) had vesicoureteral reflux. Of these, four underwent endoscopic surgical correction. Other associated urological anomalies were ureteropelvic junction obstruction (n = 6), hypospadias (n = 1), and kidney stones (n = 1). On technetium-99 m dimercaptosuccinic acid scintigraphy, which was performed in all patients, no significant association between grade of reflux and presence of scarring was seen. Hypertension was diagnosed only in one child (0.8%) who required antihypertensive treatment. The prevalence of unilateral undescended testicle in children aged <1 year in the 82 male patients was 4.9%. Seventy-six patients (59.4%) developed compensatory hypertrophy in the contralateral kidney during a 1 year follow-up period. Of the total, only seven children (5.5%) had undergone nephrectomy.

CONCLUSIONS

MCDK follows a benign course with relatively few sequelae, and therefore these patients should be closely followed up and conservatively managed.

Screening for Mullerian anomalies in patients with unilateral renal agenesis: Leveraging early detection to prevent complications

BACKGROUND

Mullerian anomalies have a known association with renal agenesis yet, to date, there are no formal recommendations for screening women with certain renal anomalies for associated genital tract disorders.

OBJECTIVE

The objective of this study is to review current data regarding the association between renal and Mullerian anomalies, and propose screening recommendations.

STUDY DESIGN

A comprehensive review of the literature was performed to identify relevant articles using the keywords "unilateral renal agenesis," "renal anomalies," and "Mullerian anomalies."

RESULTS

Over 30% of patients with unilateral renal agenesis have an associated Mullerian anomaly. However, diagnosis is frequently delayed in this population until after menarche when complications of retrograde menstruation with obstructive anomalies lead to significant problems including endometriosis, pelvic inflammatory disease, and infertility. No clear guidelines exist for communication among the antenatal sonographer, the obstetrician, the parents, and the child's pediatrician, which creates a barrier to effective screening and follow-up. Further, no current guidelines exist for screening women with certain renal anomalies for Mullerian anomalies.

DISCUSSION

The complications of Mullerian anomalies are easily preventable if identified early. We propose new guidelines for education and screening for Mullerian anomalies in patients with unilateral renal agenesis (URA) and multicystic dysplastic kidney (MCDK) to guide providers, patients, and parents on proper identification and management (Table).

CONCLUSIONS

Screening young women with URA and MCDK for Mullerian anomalies has the potential to prevent long-term complications from untreated obstructive malformations. Identification of unilateral renal agenesis on antenatal ultrasound must be clearly articulated with parents and the child's pediatrician so that proper screening can be performed before menarche. Pelvic sonography is a low-cost, high-yield screening tool to identify these anomalies.

Infants with prenatally diagnosed kidney anomalies have an increased risk of urinary tract infections

AIM

This study estimated the urinary tract infection (UTI) risk in a nationwide cohort of infants prenatally diagnosed with parenchymal kidney anomalies compared with a comparison cohort.

METHODS

A Danish population-based nationwide cohort of foetuses diagnosed with parenchymal kidney anomalies between 2007 and 2012 had previously been identified. These were compared with foetuses without kidney anomalies who were prenatally scanned the same year. Live born infants were followed from birth until the diagnosis of UTI, emigration, death or two years of age. Cumulative incidences of UTIs were computed. Mortality was estimated using the Kaplan-Meier method.

RESULTS

We identified 412 foetuses with parenchymal kidney anomalies out of 362 069 who underwent ultrasound scans and 277 were born alive. The overall risk of a UTI before the age of two years was 19%, and it was 14% among infants without prenatally diagnosed co-occurring urinary tract malformations. The corresponding risk in the 4074 controls was 1%. After two years, mortality was 2.2% in infants with prenatally diagnosed parenchymal kidney anomalies and 0.2% in the controls.

CONCLUSION

Infants prenatally diagnosed with parenchymal kidney anomalies had a substantially increased risk of UTI. Awareness of this increased risk may facilitate earlier diagnosis of UTIs in this population.

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.

Fetal MRI: A pictorial essay

Ultrasonography (USG) is the primary method for antenatal fetal evaluation. However, fetal magnetic resonance imaging (MRI) has now become a valuable adjunct to USG in confirming/excluding suspected abnormalities and in the detection of additional abnormalities, thus changing the outcome of pregnancy and optimizing perinatal management. With the development of ultrafast sequences, fetal MRI has made remarkable progress in recent times. In this pictorial essay, we illustrate a spectrum of structural abnormalities affecting the central nervous system, thorax, genitourinary and gastrointestinal tract, as well as miscellaneous anomalies. Anomalies in twin gestations and placental abnormalities have also been included.

Prenatal diagnosis of fetal multicystic dysplastic kidney via high-resolution whole-genome array

BACKGROUND

Women with fetal multicystic dysplastic kidneys (MCDK) are commonly referred for genetic counseling, for which identification of the correct etiology is a prerequisite.

METHODS

A total of 72 women with fetal MCDK at Guangzhou Women and Children's Medical Center were examined via invasive prenatal diagnosis from May 2010 to June 2015. Standard karyotyping analysis was provided to all fetuses, and chromosomal microarray with Affymetrix CytoSan HD arrays was offered to cases whose DNA samples were available.

RESULTS

Abnormal karyotypes were detected in 3 of 72 (4.17%) fetuses. Of the 69 (95.8%, 69/72) fetuses with normal karyotypes, 30 (42%, 30/69) underwent chromosome microarray analysis (CMA) testing. The CMA identified pathogenic copy number variations in five fetuses, leading to a pathogenic detection rate of 16.7% (5/30). Well-known microdeletion or microduplication syndromes including renal cysts and diabetes (RCAD) syndrome and Williams-Beuren syndrome (WBS) were identified in three cases. Moreover, four chromosomal imbalanced regions were also identified in our MCDK fetuses: 22q11.1 duplication, 4q35.2 deletion, 22q13.33 duplication and 1p33 duplication. Genes PEX26, ELN, HNF1B, ALG12, FRG1, FRG2 and CYP4A11 were possible candidates for fetal MCDK. The proportions of variants of unknown significance before and after parental analysis were 13.3% (4/30) and 3.3% (1/30), respectively.

CONCLUSIONS

In the present study, the frequency of chromosomal abnormalities in MCDK fetuses was 4.17% and all rearrangements were imbalanced aberrations. CMA was able to increase the pathogenic detection rate to 16.7% in MCDK fetuses with normal karyotype. Critical regions for RCAD syndrome, WBS and copy number variants of 22q11.1 duplication, 4q35.2 deletion, 22q13.33 duplication and 1p33 duplication were associated with fetal MCDK. Genes PEX26, ELN, HNF1B, ALG12, FRG1, FRG2 and CYP4A11 were possible candidates for fetal MCDK.

Outcome of Multi-Cystic Dysplastic Kidneys in Children

Background:

Renal cystic diseases are important causes of chronic kidney disease (CKD).

Objectives:

We report the pattern of renal cystic disease in children and evaluate the outcome of children with multicystic dysplastic kidney (MCDK).

Patients and Methods:

Retrospective study of all children with cystic kidney diseases at King Abdulaziz University hospital from 2006 to 2014.

Results:

Total of 55 children (30 males); 25 MCDK, 22 polycystic kidney diseases (PKD), 4 nephronophthises and 4 renal cysts. Consanguinity was positive in 96.2%. MCDK and simple renal cyst patients had good renal function while PKD and nephronophthisis developed renal impairment. Most MCKD were diagnosed ante-natally, 16 of them were followed up for 3.4 (1.97) year. Their last creatinine was 33.9 (13.5) umol/L. MCDK was spontaneously involuted at mean age of 2.6 (1.3) years in 56%.

Conclusions:

MCDK is the commonest cystic renal disease and diagnosed ante-natally in the majority of cases. It has a good prognosis.

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.

Neonatal polycystic kidney disease

This article provides an up-to-date comprehensive review and summary on neonatal polycystic kidney disease (PKD) with emphasis on the differential diagnosis, clinical manifestations, diagnostic techniques, and potential therapeutic approaches for the major causes of neonatal PKD, namely hereditary disease, including autosomal recessive and autosomal dominant PKD and nonhereditary PKD, with particular emphasis on multicystic dysplastic kidney. A brief overview of obstructive cystic dysplasia and simple and complex cysts is also included.

Nephrectomy for Non-neoplastic Kidney Diseases

This review discusses the pathology of non-neoplastic kidney disease that pathologists may encounter as nephrectomy specimens. The spectrum of pediatric disease is emphasized. Histopathologic assessment of non-neoplastic nephrectomy specimens must be interpreted in the clinical context for accurate diagnosis. Although molecular pathology is not the primary focus of this review, the genetics underlying several of these diseases are also touched on.

Dyserythropoiesis in a child with pyruvate kinase deficiency and coexistent unilateral multicystic dysplastic kidney

Pyruvate kinase (PK) deficiency is the commonest enzyme deficiency in the glycolytic pathway leading to hemolytic anemia secondary to decreased Adenosine Triphosphate (ATP) synthesis in the red cells. synthesis. PK deficiency due to mutations in the PKLR (1q21) gene leads to highly variable clinical presentation ranging from severe fetal anemia to well compensated anemia in adults. We describe dyserythropoiesis in the bone marrow of a child with transfusion dependent anemia and unilateral multicystic dysplastic kidney (MCDK) mimicking Congenital Dyserythropoietic Anemia type I (CDA type I). Persistently low erythrocyte PK levels and double heterozygous mutations present in the PKLR gene confirmed the diagnosis of PK deficiency.

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 center experience in patients with unilateral multicystic dysplastic kidney

OBJECTIVE

To determine the clinical features, long-term outcomes, and additional urological anomalies of patients treated for multicystic dysplastic kidney (MDK).

MATERIALS AND METHODS

Patients with MDK who were followed between January 2004 and October 2012 were reviewed retrospectively. Demographic, clinical, laboratory, and radiological data were evaluated.

RESULTS

A total of 68 patients with MDK were followed for a mean period of 46.8 ± 32.4 months. MDK was detected by antenatal ultrasound in 64 (94.1%) of the patients. Ten patients had (14.7%) additional urological anomalies in contralateral kidney. Vesicoureteral reflux was found in five patients (7.3%). Other urological anomalies were megaureter (two), cortical renal cyst (two), ureteropelvic junction obstruction (one), and renal ectopy (one). Urinary tract infection was detected in 14 (20.5%) patients. Four (5.9%) patients had hypertension. Compensatory hypertrophy was detected in 29 (42.6%) patients. Eight (11.8%) of these 29 patients had glomerular hyperfiltration and three (4.4%) of these eight patients also had proteinuria. Follow-up ultrasound revealed complete involution in 19 (35.8%) patients. Nephrectomy was performed in 15 (22.0%) patients. Indications of nephrectomy were, recurrent urinary infection (four), hypertension (three), ureterocele (two), renal calculi (one), flank pain (one), hematuria (one), persistent large cystic kidney (three), and atypical US findings (two).

CONCLUSION

In patients with MDK, depending on the clinical, laboratory, and radiological findings, appropriate timing of operation by multidisciplinary approach is important for early detection and treatment of any possible complications.

Multicystic dysplastic kidney complicated by pyelonephritis

Patient: Female, 21

Final Diagnosis: Multicystic Dysplastic Kidney Disease complicated by pyelonephritis

Symptoms: Left flank pain (CVAT) • dysuria • fever

Medication: Levofloxacin

Clinical Procedure: Dimercaptosuccinic acid scan • voiding cystouretrogram

Specialty: Nephrology

The relationships between renal compensatory hypertrophy etiologic factors and anthropometric development in the pediatric age group

OBJECTIVE

To evaluate the factors associated with compensatory hypertrophy in the functional kidneys of children.

METHODS

The medical files of patients with a solitary functional kidney were reviewed retrospectively. Data regarding anthropometric measurements, functional renal length, functional renal length of standard deviation score (SDS) of functional kidney at diagnosis, and end of follow-up were obtained. Patients were divided into 2 groups, those with a unilateral kidney function of <10% (hypoplasia, dysplasia, and atrophy, group 1) and those with a solitary kidney (agenesis, and multicystic dysplastic kidney, group 2).

RESULTS

A total of 126 patients (70 boys) were evaluated. Both the sizes of the functional kidney and functional kidney SDS values at diagnosis were greater in group 1 relative to group 2. At the end of the follow-up period, anthropometric values including functional kidney size were higher in group 2. Functional kidney size of 2 SDS above the normal was mostly predictive at age 17.5 months (odds ratio [OR] 5.06) and at a body height of 82 cm (OR 5.57).

CONCLUSION

The most determining factors for renal length SDS values were age and height. Solitary kidneys complete compensatory hypertrophy by 17.5 months of age, and after that their growth continues in parallel to normal growth.

Autosomal dominant polycystic kidney disease with ectopic unilateral multicystic dysplastic kidney

Background

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary renal disorder. In most cases, ADPKD similarly affects bilateral kidneys.

Case presentation

Among the 605 ADPKD patients that were followed up by our center, we identified two male patients with unilateral ADPKD. The cases were remarkable because the patients also had ectopia and multicystic dysplasia in the contralateral kidney, which are generally sporadic disease conditions. Both patients tested positive for polycystic kidney disease 1 mutation, but negative for hepatocyte nuclear factor 1 beta mutation. Moreover, the deterioration of their kidney function seemed to be quicker than their age- and sex-matched controls and siblings. Both patients had started a long-term hemodialysis in their 40s.

Conclusion

Anatomical and genetic abnormality in patients with ADPKD may be more frequent and complex than previously believed. The compensatory capacity in patients with ADPKD is fragile, and missing one kidney could accelerate the deterioration of renal function.

Risk factors for renal injury in children with a solitary functioning kidney

OBJECTIVE

The hyperfiltration hypothesis implies that children with a solitary functioning kidney are at risk to develop hypertension, proteinuria, and chronic kidney disease. We sought to determine the presenting age of renal injury and identify risk factors for children with a solitary functioning kidney.

METHODS

We evaluated 407 patients for signs of renal injury, defined as hypertension, proteinuria, an impaired glomerular filtration rate, and/or the use of renoprotective medication. Patients were subdivided on the basis of type of solitary functioning kidney and the presence of ipsilateral congenital anomalies of the kidney and urinary tract (CAKUT). The development of renal injury was analyzed with Kaplan-Meier analysis. Risk factors were identified by using logistic regression models.

RESULTS

Renal injury was found in 37% of all children. Development of renal injury increased by presence of ipsilateral CAKUT (odds ratio [OR] 1.66; P = .04) and age (OR 1.09; P < .001). Renal length was inversely associated with the risk to develop renal injury (OR 0.91; P = .04). In all patients, the median time to renal injury was 14.8 years (95% confidence interval 13.7-16.0 years). This was significantly shortened for patients with ipsilateral CAKUT (12.8 years, 95% confidence interval 10.6-15.1 years).

CONCLUSIONS

Our study determines independent risk factors for renal injury in children with a solitary functioning kidney. Because many children develop renal injury, we emphasize the need for clinical follow-up in these patients starting at birth.

Cowden disease and multicystic dysplastic kidney: increased risk of renal cancer?

Unilateral multicystic dysplastic kidney is one of the most frequently identified urinary tract abnormalities in children. Although it can be an isolated finding, it is often associated with other anomalies of the kidney and urinary tract. It has also been described in association with other multisystemic disorders of known genetic aetiologies. Cowden disease (CD) is a rare autosomal-dominant disorder with age-related penetrance characterized by benign and malignant hamartomatous lesions affecting derivatives of all three germ cell layers. Hamartomas can emerge in virtually every organ, but are mostly found in the skin and gastrointestinal tract. We report a 7-year-old patient presenting with unilateral multicystic dysplastic kidney and CD, a hitherto unknown association in paediatrics, which raises the question of an increased risk of renal cancer.

Pediatric renal diseases in the Kingdom of Saudi Arabia

BACKGROUND

Pediatric nephrology is a growing subspecialty in the Kingdom of Saudi Arabia (KSA). Pediatric nephrologists are challenged with a different spectrum of renal diseases. Moreover, there is a lack of epidemiological studies for most of these diseases. In this article, we discuss the spectrum of renal diseases in KSA and highlight the differences that exist between reports from KSA and those from other countries.

DATA SOURCES

PubMed and MEDLINE databases were searched for articles on pediatric renal diseases.

RESULTS

Genetically mediated renal diseases are considerably high in KSA. Congenital and infantile nephrotic syndrome is higher in KSA than in other countries. Post-infectious glomerular pathology is rather common but is declining, while tropical infections such as schistosomiasis have been controlled. Neurogenic bladder caused by spinal lesion is an important cause of chronic kidney disease among pediatric patients. Renal stones are also more frequent in KSA than in other countries.

CONCLUSIONS

The spectrum of pediatric renal diseases in KSA is rather different from that reported from Western countries. More epidemiological studies are required to understand the actual incidence and nature of these diseases.

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.