Renal cell carcinoma arising in a multicystic dysplastic kidney

Association of Wilms tumor in multicystic dysplastic kidneys: case report and review of the literature

Multicystic dysplastic kidney is a rare urinary anomaly characterized by multiple non-communicating cysts resulting in a non-functional kidney. In addition to association with hypertension and contralateral renal anomalies, children with multicystic dysplastic kidney have an increased risk of Wilms tumor. Cohort studies and systematic reviews are hampered in estimating the true risk of this association due to the rarity and infrequent reporting of the condition. We present a case of a 2-year-old male child with an antenatal diagnosis of multicystic dysplastic kidney undergoing surveillance ultrasonography who presented with a symptomatic Wilms tumor.

Level of evidence: Not applicable for this multicentre audit.

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.

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.

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.

[Cystic diseases of the kidney]

Cystic diseases of the kidney constitute a heterogeneous family. Most renal cysts are benign and asymptomatic, and don't have any impact on renal function. These "simple" cysts are usually managed conservatively. However, some renal cysts may be symptomatic or may have atypical radiological presentation, leading to suspicion of malignant tumour; puncture or surgical investigation may be indicated in such cases. The other cystic renal diseases include specific entities, either genetic or acquired during development. Some malformative syndromes are often associated, and renal function may be impaired. In such cases, nephrectomy is required.

Prenatal intervention for urinary obstruction and myelomeningocele

Widespread use of ultrasonography has resulted in an increase in the recognition of fetal hydronephrosis. The enthusiasm that accompanied early interventions has been tempered by the experience and results obtained over the past 2 decades. The goal has remained the same: to identify patients with serious prenatal obstruction and to identify those which may benefit from intervention. Myelomeningocele remains a devastating congenital anomaly. Fetal and experimental studies suggested that patients with myelomeningocele could benefit from prenatal intervention. Advances in technology and perinatal management have made intervention for more complex malformations such as myelomeningocele possible. This article will review current knowledge and will detail rational management for the management of prenatal hydronephrosis. The current state of antenatal myelomeningocele repair and the urologic implications will be described as well.

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.

Non-Wilms' renal tumors in children

Renal tumors other than Wilms' tumors are infrequent in childhood. Wilms' tumors account for 6% to 7% of childhood cancer, whereas the remaining renal tumors account for less than 1%. The most common non-Wilms' tumors are clear cell sarcoma of the kidney, rhabdoid tumor of the kidney, renal cell carcinoma, mesoblastic nephroma, and multilocular cystic nephroma. Collectively, these tumors account for less than 10% of the primary renal neoplasms in childhood.

Renal growth characteristics in children born with multicystic dysplastic kidneys

OBJECTIVES

To report on the growth characteristics of the affected and contralateral kidneys in children born with multicystic dysplastic kidneys (MCDKs).

METHODS

Thirty-three patients were enrolled from 1970 to 1995: 23 were initially managed nonoperatively (mean follow-up 3.39 years), and 10 underwent nephrectomy. Patients underwent radionuclide renal imaging and contrast voiding cystography. Serial ultrasonography was used to obtain measurements of the affected and contralateral kidneys. Blood pressure measurements and serum creatinine levels were available in some patients.

RESULTS

Among the 23 nonoperative patients, the affected MCDK involuted in 4 patients during a mean follow-up of 4.5 years at a rate of 1.02 cm/yr (24% annually); 7 kidneys decreased in size at a mean rate of 0.38 cm/yr (5.8% annually); 6 grew at a mean rate of 1.16 cm/yr (9.9% annually); 1 kidney did not change in size; and 5 children were lost to follow-up. The mean size of the contralateral kidneys at birth was 5.3 cm, 2 standard deviations larger than normal. Over time, this relative hypertrophy was maintained at a growth rate of 0.89 cm/yr (18.5% annually). Two patients who had undergone nephrectomy also had serial postoperative ultrasonic renal measurements, and contralateral growth was 0.61 cm/yr (12.16% annually). All but 1 patient had normal blood pressure measurements and serum creatinine levels.

CONCLUSIONS

Most MCDKs involute or decrease in size over time, although this may take many years. Contralateral hypertrophy is seen at birth and is maintained during childhood growth, regardless of whether the affected kidney is removed. There is no associated hypertension or malignancy when the dysplastic kidney is left in place.

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.

Renal dysplasia: an autopsy study of associated congenital malformations

A retrospective analysis of infant autopsies in the last 14 years was done with the aim of determining the frequency of associated malformations. Renal dysplasia comprised 36 of 594 autopsies done and was the commonest congenital urologic malformation (6.06% of all infant autopsies). Histologically all cases were characterised by hallmarks of disordered metanephric differentiation and organisation. Extrarenal malformations were seen in all (100%) of the cases of which other urologic anomalies were the commonest (28) followed by those of musculoskeletal (18), gastrointestinal (13), cardiovascular (10) and central nervous system (6). Syndromic association was seen in 5 (14%) cases. There were twenty two percent still births and 47% infants died perinatally. A thorough search for systemic malformations is mandatory in all cases of renal dysplasia as these may influence the survival significantly. Cystic renal dysplasia should be differentiated from other causes of cystic renal diseases.

Wilms tumor and multicystic dysplastic kidney disease

PURPOSE

There is ongoing controversy concerning the management of multicystic dysplastic kidney disease, particularly with regard to the potential for malignant transformation. Our report fuels the debate by adding the 2 youngest patients in whom malignancy was present from birth or developed subsequently.

MATERIALS AND METHODS

Two well documented cases of malignancy associated with multicystic dysplastic kidney disease are presented in 2 female infants (5 and 3 months old). The 5-month-old female infant was followed for multicystic dysplastic kidney disease and had no evidence of tumor either antenatally or at birth. The 3-month-old presented with hypertension and interventricular septal defect. A renal tumor was present on initial ultrasound.

RESULTS

Even though malignant degeneration is rare in multicystic dysplastic kidney disease, 9 cases have been reported in the literature so far. Of these cases 3 were Wilms tumor, 5 were renal cell carcinomas and 1 mesothelioma.

CONCLUSIONS

Our 2 cases lend support to the surgical management of multicystic dysplastic kidney disease, particularly as nephrectomy can now be performed in a day surgery setting with minimal morbidity. Only the risks of coexisting malignancy and possible malignant degeneration transformation are specifically addressed in this article. Other complications of multicystic dysplastic kidney disease such as hypertension, infection, abdominal pain, hematuria and persistent dysplastic renal tissue despite ultrasonographic resolution of multicystic dysplastic kidney disease are additional risk factors to be considered. A recommendation for nephrectomy in all cases of multicystic dysplastic kidney disease cannot be based only on these 2 cases. Several other factors must be weighed before making that decision.

The importance of accurate diagnosis and early close followup in patients with suspected multicystic dysplastic kidney

PURPOSE

Conservative management of children who have unequivocal multicystic dysplastic kidney with a stable or regressive pattern of disease during close followup is well established. However, a clear diagnosis may prove difficult. We report 3 cases in which the diagnosis was particularly difficult to increase awareness of the importance of applying strict criteria for the diagnosis of multicystic dysplastic kidney.

MATERIALS AND METHODS

Three children in whom a diagnosis of multicystic dysplastic kidney was suspected underwent surgical exploration. One patient who did not comply with followup presented with a large retroperitoneal mass suspicious for neuroblastoma 8 months later. In another patient a growing renal cystic mass was suspicious for a multilocular cyst at 3 months of followup. At 2 months of followup a cystic nephroma was suspected in the remaining patient.

RESULTS

All patients underwent surgical exploration. The patient with suspected neuroblastoma had extensive stage 3 Wilms tumor. In the child with a suspected multilocular cyst segmental multicystic dysplastic kidney of the lower pole of an ipsilateral duplicated system was found. In the patient in whom cystic nephroma was suspected mesoblastic nephroma was confirmed by the National Wilms Tumor Study Pathology Center.

CONCLUSIONS

An unequivocal diagnosis of multicystic dysplastic kidney should be made early in life. The urologist should have an active role in making the initial radiological diagnosis and close followup with renal ultrasound every 3 to 4 months is essential during year 1 of life. Surgical exploration is indicated if the diagnosis becomes equivocal at any point or should concerns exist regarding compliance with followup.

Insurability of children with congenital urological anomalies

PURPOSE

We sought to determine life insurance underwriting practices for children diagnosed with multicystic dysplastic kidney or unilateral neonatal hydronephrosis, and evaluate whether management options (observation versus operative intervention) have an influence on such practices.

MATERIALS AND METHODS

A questionnaire and history of 1 child with multicystic dysplastic kidney and 1 with unilateral neonatal hydronephrosis were distributed to 348 insurance companies licensed to issue life insurance policies in New Jersey. The medical director of each insurance company was requested to indicate the current underwriting practices for life insurance policies based on these 2 case scenarios, and asked whether observation or operative intervention influenced such decisions.

RESULTS

Of the 348 insurance companies licensed to issue life insurance 130 (37.4%) responded, including 5 (3.8%) that did not choose to participate in the study, 56 (43.1%) that did not issue life insurance to children and 69 (53.1%) that completed the questionnaire based on current life insurance underwriting practices. For a child with multicystic dysplastic kidney 10 companies (14.5%) would issue life insurance if treatment involved observation only, while 49 (71%) would do so after nephrectomy. For a child with unilateral neonatal hydronephrosis 19 (27.5%) companies would issue life insurance if treatment involved observation only, while 46 (66.7%) would do so after pyeloplasty.

CONCLUSIONS

Despite limited long-term data on and uncertainty about the natural course of multicystic dysplastic kidney and unilateral neonatal hydronephrosis, treatment options offered a child with a congenital urological anomaly may have a significant impact on the ability to obtain life insurance. Children with multicystic dysplastic kidney and unilateral neonatal hydronephrosis can usually obtain life insurance after early operative intervention (nephrectomy and pyeloplasty, respectively), although sometimes at higher cost.

Unilateral multicystic dysplastic kidney: the case for nephrectomy

Management of unilateral multicystic dysplastic kidneys (MCDK) presents physicians and surgeons with a significant dilemma. Recent studies have indicated that the incidence of short term complications of MCDK is low and many authors have recommended conservative non-operative treatment. Surgery has been proposed by some because of the potential complications of hypertension, infection, and malignant change. Three children with hypertension secondary to MCDK seen at this institution in the past four years, one of whom had been discharged from follow up as a result of 'disappearance' of the cystic kidney on ultrasound examination, are reported. We believe that the risks of hypertension secondary to MCDK have been understated, and that based on the conclusions of these studies, many children may be receiving suboptimal follow up. We currently favour elective nephrectomy as the treatment of choice for this lesion.

Outpatient nephrectomy for nonfunctioning kidneys

We describe a surgical approach that allows multicystic dysplastic and nonfunctioning hydronephrotic kidneys to be removed on an outpatient basis through a 2.5 to 3 cm. subcostal incision. In the last 5 years 40 children (age 4 months to 5 years, mean 8.2 months) were scheduled for outpatient nephrectomy in an ambulatory surgical unit in a hospital setting. Of the 40 patients 30 had a multicystic kidney. Renal size ranged from 3 x 2 to 9.5 x 7.2 cm. Operative time ranged from 20 to 70 minutes (mean 45.4). In 34 cases (85%) an intercostal block was also performed to provide analgesia for 18 to 24 hours. Nephrectomy was done on an outpatient basis in 39 of the 40 children (98%). Mean pain score (range 0 to 5) in the last 19 patients who underwent an intercostal block was 0.68 at discharge from the hospital, 0.85 at bedtime and 0.95, 24 hours later. We conclude that nephrectomy may be performed through a small incision on an outpatient basis with minimal morbidity, and that this approach offers an alternative to laparoscopic nephrectomy and nonsurgical management of these kidneys.

Multicystic renal dysplasia diagnosed in the antenatal period: a note of caution

OBJECTIVE

To document the urological problems associated with multicystic renal dysplasia (MCRD), to assess the efficacy of radiological methods for following the natural history of MCRD and to review current experience in the light of historical data regarding this condition.

PATIENTS AND METHODS

From January 1982 to December 1992 data were obtained prospectively on 62 patients (41 boys and 21 girls, age range 1-11 years) who had a diagnosis of MCRD suspected on antenatal ultrasonography. All patients had the diagnosis confirmed with radioisotope scans and micturating cystograms. Serum creatinine was measured in each patient and repeated clinically as indicated. Follow-up was from 1 to 11 years, with a clinical review and an annual ultrasonogram. The natural history of these patients was compared with those in other published studies.

RESULTS

Of the 62 patients, 12 had associated vesicoureteric reflux. Four patients developed impaired renal function during the course of observation and 10 patients required urological surgery for other pathologies. In the patients managed conservatively, 38% underwent no resolution on sequential ultrasonograms during the 2-year follow-up, and in four children, where complete resolution of the MCRD had occurred on ultrasonography, significant cellular renal masses were excised at subsequent surgery.

CONCLUSION

Patients with MCRD have significant associated urological malformations and the natural history in such patients is unpredictable. We do not regard MCRD as an entirely benign condition and feel that all patients require appropriate investigation of their urinary tract and long-term follow-up where conservative treatment is instituted. From the natural history of these patients, reviewed in conjunction with the literature, we recommend that decisions for management can only be taken with the full informed consent of the parents and that surgical excision is offered as part of that process.

Renal cell carcinoma arising in a regressed multicystic dysplastic kidney

Controversy surrounds the management of multicystic dysplastic kidney. Recent advances in radiological imaging have resulted in a higher incidence of its detection, and they provide an accurate noninvasive means of diagnosis and followup. Consequently, the need for surgical removal of these lesions is being reevaluated. We report a case of renal cell carcinoma arising from solid renal dysplasia associated with a regressed multicystic dysplastic kidney. We emphasize the potential risk of nonoperative management of these lesions and further define the spectrum of malignant degeneration associated with renal dysplasia.

Multicystic dysplastic kidney: another application of 99mTc MAG3

The value of 99mTechnetium-mercapto acetyl triglycine (99mTcMAG3) in the investigation of 10 children with suspected multicystic dysplastic kidney (MCDK) has been assessed. The condition has to be distinguished from hydronephrosis, usually caused by pelviureteric junction obstruction. Based on our findings, we propose that 99mTc MAG3 replace 99mTc DMSA because it allows a better assessment of the contralateral kidney and permits a full assessment where the diagnosis is hydronephrosis rather than MCDK.

Outcome of antenatally detected cystic dysplastic kidney disease

Forty four fetuses with multicystic dysplastic kidney (MCDK) disease recognised on antenatal ultrasound were studied prospectively. In nine aborted fetuses and in five who died in the neonatal period the MCDK disease was bilateral or there were associated lethal abnormalities or syndromes. All surviving infants had unilateral disease and in six (20%) there was significant reflux into the normal contralateral kidney. Since 1988 the management of unilateral MCDK disease has been conservative with no child developing sepsis, hypertension, or malignancy. Serial ultrasound examinations suggest that MCDK lesions involute with time and conservative rather than operative management is favoured.

Wilms' tumor arising in a multicystic kidney

We describe a child with Wilms' tumor (WT) which occurred in an unequivocal multicystic dysplastic kidney (MDK). We indicate a current nonsurgical approach to MDK, but stress the probable malignant degeneration of blastemal cells, the need to search carefully for the WT in the MDK, and the necessity on 3-monthly follow-up US studies.

renal tumors and tumor-like lesions in pediatric patients

Renal enlargement presenting as an abdominal mass(es) is attended by a lengthly differential diagnosis of non-neoplastic and neoplastic lesions with a range in serious connotations and consequences. Simple compensatory hypertrophy and unilateral multicystic dysplasia are relatively innocuous and easily recognized with appropriate imaging studies; they are also related in the sense that the normal contralateral kidney hypertrophies in the absence of a non-functioning dysplastic kidney. Bilateral nephromegaly in a neonate is generally a sign of autosomal recessive polycystic kidney disease or multicystic dysplasia secondary to distal obstructive uropathy. Primary neoplasms of kidney in the pediatric population in the past were traditionally classified as Wilms' tumors, but that erroneous practice has been eliminated with the recognition of several distinctive neoplasms in addition to classic Wilms' tumor. Separating a typical Wilms' tumor from mesoblastic nephroma, clear cell sarcoma of the kidney and the malignant rhabdoid tumor, for treatment and prognostic purposes, has become the accepted norm in the past 12-13 years. Another important advance at the cellular level is the recognition of a deletion in the short arm of chromosome 11 in the cultured cells of Wilms' tumor and in the germ cell line in certain clinical settings of Wilms' tumors. A dramatic expansion in the understanding and management of childhood renal neoplasms has occurred through the multimodality approach of laboratory investigation and applied clinical research.

Multicystic renal dysplasia detected by prenatal ultrasonography. Natural history and results of conservative management

In a review of 44 infants with multicystic renal dysplasia diagnosed prenatally by ultrasonography, contralateral anomalies, bilateral disease and other non-urinary congenital anomalies were rare. In approximately two-thirds of infants the lesion was impalpable and in 2 cases involution had occurred prenatally. All but 5 were managed conservatively and without complications, and partial or complete involution of the lesion occurred in more than 50% during follow-up. It was concluded that the natural history of this anomaly is usually benign and that conservative management is advisable.

Hypertension as a complication of multicystic dysplastic kidney

The detection of multicystic dysplastic kidney in utero using prenatal ultrasound is becoming a more frequent occurrence. An accurate diagnosis of multicystic dysplastic kidney usually can be made radiographically, and therefore the main indication for surgery in the asymptomatic patient may be the potential risk of complications developing later in life. We report hypertension as a complication of multicystic dysplastic kidney and review the literature.

Flow cytometric evaluation of multicystic dysplastic kidneys

The most appropriate management of the multicystic dysplastic kidney remains controversial. At issue is the long-term risk of the development of malignancy in the multicystic dysplastic kidney. The association between renal dysplasia and neoplasia has not been confirmed, with only 6 cases of malignancy reported. Nephroblastomatosis, a probable precursor of Wilms tumor, has been found in 5 to 7% of the cases of multicystic dysplastic kidney when specifically sought. In an attempt to determine whether a relationship exists between renal dysplasia and neoplasia in terms of abnormalities of cellular deoxyribonucleic acid content we performed flow cytometric evaluation on 30 formalin fixed, paraffin embedded archival specimens of multicystic dysplastic kidneys. None of the kidneys had evidence of malignancy. Nuclear deoxyribonucleic acid ploidy studies were performed on single dissociated nuclei prepared by the technique of McLemore and associates and stained with propidium iodide. All specimens demonstrated a diploid pattern of deoxyribonucleic acid, including 3 specimens with nephroblastomatosis or extensive papillary growth, and no specimen demonstrated a tetraploid or aneuploid pattern. The mean G0/G1 fraction was 85.94% (standard deviation 4.59) and the mean S/G2/M fraction was 12.54% (standard deviation 4.72). These findings do not support or negate the potential for neoplasm associated with multicystic dysplastic kidney, since a diploid deoxyribonucleic acid pattern does not eliminate the possibility of the future development of malignancy.

Long-term follow-up of children with renal carcinoma

Renal carcinoma is a rare tumour in children. The clinical, histological and follow-up details of 6 patients are presented. Haematuria is confirmed as an important indicator of renal pathology. Long-term follow-up suggests that chemotherapy and radiotherapy have little effect on the prognosis in advanced disease.

Hypertension and multicystic kidney

The optimal management of the asymptomatic patient with a multicystic kidney remains a dilemma. The risk of nephrectomy in a neonate or infant with this lesion is small and the morbidity is minimal. The alternative to elective nephrectomy is life-long follow-up with blood pressure determinations, beginning in infancy. We report herein two infants with multicystic kidney (MCK) in whom hypertension was cured by its removal. Since accurate blood pressure measurements are relatively difficult to obtain in infants and since periodic long-term follow-up is difficult in the best of circumstances, we are concerned that hypertension caused by a retained MCK goes undiagnosed perhaps more frequently than a review of the current literature suggests. Such hypertension may result in contralateral renal damage and arteriosclerosis, so that later removal of the MCK may not have a beneficial effect on the elevated blood pressure.

Nodular renal blastema in the multicystic kidney

Of 60 surgically removed multicystic, dysplastic kidneys examined for the presence of nodular renal blastema only 1 (2 per cent) had blastematous elements. Of the 60 patients 35 were from the authors' personal series and they were examined in clinical detail. The results of this study and those in the literature are discussed in relation to the over-all management of the asymptomatic multicystic, dysplastic kidney.

Wilms tumorlet, nodular renal blastema and multicystic renal dysplasia

We reviewed 60 cases of multicystic renal dysplasia collected during a 10-year period. Differentiated nonproliferative nodular renal blastema occurred in 6.7 per cent of the cases, which is similar to the incidence of nodular renal blastema in kidneys of other infants with congenital obstructive uropathy. A unique case of cystic dysplasia containing nodular renal blastema and Wilms tumorlet indicates the possibility that a persistently proliferative nephroblastomatous lesion may rarely occur.

Multicystic dysplastic kidney: is nephrectomy still appropriate?

We analyzed 25 cases of multicystic kidney to assess the impact of prenatal diagnosis on the management of this condition. The incidence of unilateral multicystic kidney was 1 in 4,300 live births. Of the 23 children with unilateral multicystic kidneys only 3 (13 per cent) had a readily palpable lesion. These findings suggest that multicystic kidney is a more common renal anomaly than was previously recognized and that the majority of cases remained undiagnosed before the advent of prenatal diagnosis. Ultrasound re-evaluation in 11 children suggests that the natural history of multicystic kidneys is towards spontaneous involution. Two kidneys were not identifiable by followup ultrasound. Hypertension and malignancy complicating multicystic kidney are reported infrequently. The literature on hypertension does not generally support the view that multicystic kidney poses a significant risk of hypertension in later childhood or adult life. We believe that the routine removal of multicystic kidneys in infancy is no longer appropriate.