5.7Associated Anomalies

•Multicystic dyplastic kidney is associated with contralateral renal disease in a significant number of patients.

•Previous reports have shown that MCDK is associated with a 20–45 % incidence of contralateral renal anomalies.

•The most common contralateral abnormality was vesicoureteral reflux and ureteropelvic junction obstruction.

•Bilateral MCDK was reported in 19 % and contralateral renal agenesis in 11 %.

•Contralateral hydronephrosis was seen in 7 %.

•30–35 % of fetuses with MCDK have associated non-renal abnormalities.

•The most common abnormalities were those of the heart, followed by the spine, extremities, face and umbilical cord.

•Fetuses with bilateral MCDK are more likely to have associated non-renal abnormalities (66.7 %) in comparison with fetuses with unilateral MCDK (25.6 %).

•Abnormal chromosomes:

–Abnormal chromosomes (10 %).

–Female fetuses (20 %) are more likely to have an abnormal chromosome study than male fetuses (5.6 %).

–Fetuses with bilateral MCDK disease (16.7 %) are more likely to have an abnormal karyotype than fetuses with unilateral MCDK (7.7 %).

–No karyotype abnormalities were found in fetuses with unilateral MCDK if an associated non-renal abnormality was not found.

•The ratio of male to female fetuses was 2.4:1.

•Female fetuses were twice as likely to have bilateral MCDK as males.

•Vesicoureteic reflux in the contralateral kidney (23 %).

•As most patients with multicystic dysplastic kidneys have pelvo-ureteral atresia on the affected side, it is unlikely that infected urine will reflux into the kidney.

•Multicystic dysplastic kidney has been reported in various syndromes, including the following:

–49,XXXXX syndrome (hypertelorism, epicanthic folds, microcephaly, short neck, clinodactyly of the fifth finger, small hands and feet, and mental retardation).

–Alagille syndrome (liver disease, cardiac defects, characteristic facies, renal anomalies, vascular anomalies and anomalies of the eye, pancreas, and skeletal system. The condition is associated with mutations in the JAG1 gene that encodes for a ligand of Notch.

–Beckwith-Wiedemann syndrome (macrosomia, microcephaly, macroglossia, visceromegaly, omphalocele, and hypoglycemia).

–Branchio-oto-renal (BOR) syndrome (hearing loss, ear malformations, branchial cleft fistulas or cysts, and renal dysplasia or renal agenesis. The BOR syndrome is an autosomal dominant condition caused by mutations in the EYA1 and SIX1 genes.

–Hypoparathyroidism-deafness-renal syndrome (sensorineural deafness, hypoparathyroidism, and urinary tract anomalies, including renal dysplasia). This autosomal dominant syndrome is caused by mutations in the GATA3 transcription factor.

–Joubert syndrome (hypoplasia of the cerebellar vermis, hypotonia, and impaired psychomotor development together with abnormal respiratory pattern, abnormal eye movements with poor vision, or both). This syndrome is an autosomal recessive condition.

–Maturity-onset diabetes of the young type V (MODY5): MODY5 is a monogenic form of diabetes with an autosomal dominant mode of inheritance caused by mutations in the hepatocyte nuclear factor 1-beta mutations. Patients present with diabetes, usually when younger than 25 years, with a wide spectrum of renal anomalies, including cystic dysplasia.

–Renal coloboma syndrome (RCS): The RCS is an autosomal dominant condition caused by mutations in the transcription factor PAX2 and characterized by optic

nerve coloboma and renal malformations, including dysplasia.

–Trisomy 18: Patients with trisomy 18 have a prominent occiput, micrognathia, low-set ears, and flexion deformities of the fingers, congenital heart disease, and mental retardation.

–VACTERL association: The VACTERL association refers to the combination of vertebral defects (V), anal atresia (A), cardiovascular anomalies (C), tracheoesophageal fistula (TE), renal anomalies (R), and limb defects (L). In 20 % of these patients, cystic renal disease may be found.

–Waardenburg syndrome type 1: Patients present with developmental anomalies of the eyelids, eyebrows, and nose root; pigmentary defects of the iris and hair; and congenital deafness.

–Williams’ syndrome: This syndrome is characterized by elfin facies, mental retardation, supravalvular aortic stenosis, and neonatal hypercalcemia.

•Nonrenal malformations reported in patients with multicystic dysplastic kidney include the following:

–Gastrointestinal malformations:

•Duodenal atresia

•Esophageal atresia

•Hirschsprung’s disease

•Anorectal malformations

•Inguinal hernia

•Omphalocele

•Tracheoesophageal fistula

–Neurologic malformations

•Anencephaly

•Caudal agenesis

•Caudal regression syndrome

•Congenital deafness

•Hydrocephalus

•Mental retardation

•Microcephaly

•Microphthalmia

•Myelomeningocele

•Spina bifida

–Cardiovascular malformations

•Aortic stenosis

•Coarctation of the aorta

•Patent ductus arteriosus

•Pulmonary stenosis

•Truncus arteriosus

•Ventricular septal defect

–Musculoskeletal

•Clinodactyly of the fifth finger

•Congenital dislocation of the hip

•Flexion deformities of the fingers

•Syndactyly

•Talipes equinovarus

–Miscellaneous

•Bipartite uterus

•Cleft palate

•Epicanthic folds

•Hymenal atresia

•Hypertelorism

•Low-set ears

•Macroglossia

•Macrosomia

•Micrognathia

•Pigmentary defects of iris and hair

•Preauricular pit

•Short neck

•Urinary malformations associated with multicystic dysplastic kidney include the following:

–Bladder wall diverticulum

–Contralateral renal agenesis

–Dysplasia

–Hypoplasia

–Crossed fused renal ectopia

–Cystic dysplasia of the testis

–Ectopic kidney

–Fibromuscular dysplasia

–Horseshoe kidney

–Patent urachus

–Seminal vesicle abnormalities

–Ureterocele

–Contralateral ureteropelvic junction obstruction has been reported in 7–12 % of patients.

–Posterior urethral valves

–Contralateral vesicoureteral reflux is reported in 4–19 % of patients.

•In children older than 2 years, 72 % of patients with multicystic dysplastic kidney showed compensatory growth of the contralateral kidney.

5.8Clinical Features

•Most cases of multicystic dysplasia of the kidney (MCDK) are detected during fetal ultraso-

nography and are reported as early as 15 weeks’ gestation.

•An abdominal mass in the flank of an otherwise healthy newborn was the most common clinical presentation of unilateral multicystic dysplastic kidney.

•The abnormal kidney is palpable in only 13–22 % of patients.

•The mass is usually mobile, ballotable, and irregular in shape, nontender, and might transilluminate.

•Multicystic dysplastic kidney is usually asymptomatic and can remain undetected into adulthood.

•Abdominal or flank pain and respiratory distress are uncommon symptoms because of the pressure effect of the abnormal kidney.

•Multicystic dysplastic kidney might be discovered during an investigation for urinary tract infection (UTI), voiding dysfunction, or hypertension. Multicystic dysplastic kidney may also be discovered when diagnostic imaging studies are performed to investigate a nonurinary problem.

•Bilateral multicystic dysplastic kidney usually results in stillbirth or death within the first few days of life; however, an infant with bilateral multicystic dysplastic kidney who survived for 17 days was reported.

•Bilateral multicystic dysplastic kidney is usually associated with oligohydramnios, amnion nodosum, pulmonary hypoplasia, and Potter facies.

•Infants with bilateral multicystic dysplastic kidney who survive have renal failure from birth and require dialysis from the first day of life.

5.9Investigations

•CBC

•Serum electrolytes, BUN and creatinine

•Urine analysis and culture

•Abdominal radiograph may show a soft tissue density with displacement of the bowels in

those with enlarged MCDK. Rarely, ring like calcifications of the cyst walls may be seen on plain radiographs.

•Abdominal ultrasound is the preferred initial examination.

–Ultrasonography is an excellent diagnostic test for MCDK, with a high degree of confidence.

–Currently, the majority of MCDK cases are diagnosed by antenatal ultrasound examination.

–Abdominal ultrasound is accurate, and it does not require sedation, radiation, and can be repeated easily.

–The cysts of MCDK may become enlarged, may shrink, or may involute during fetal life.

–Bilateral MCDK may occur with oligohydramnios as a result of poor urine production.

–In patients with a prenatal diagnosis of MCDK, a postnatal ultrasound should be done prior to discharge to differentiate MCDK from hydronephrosis.

–Abdominal ultrasounds characteristically show:

•Hypoechoic cysts of variable sizes and shapes

•Interfaces between cysts

•A nonmedial location of large cysts

•The absence of an identifiable renal sinus

•Lack of communication between cysts

•Minimal surrounding parenchyma

–An obstructive uropathy with little renal parenchyma can mimic MCDK, but radionuclide studies can provide confirmation of the diagnosis.

–The presence of a kidney shape and/or a large cystic structure in the medial portion of the kidney on ultrasound evaluation are more suggestive of hydronephrosis than MCDK. In MCDK, the cysts do not communicate, while in hydronephrosis there is communication with the central renal pelvis.

–The autosomal recessive polycystic kidney disease (PCKD) is not usually mistaken for MCDK, as the cysts in PCKD are too small

to be visualized on sonograms, and the parenchyma is generally homogeneously hyperechoic.

•Radionuclide scan:

–Radionuclide scan is useful in differentiating an obstructed functioning kidney from MCDK.

–Radionuclide scan may be necessary if ultrasonography does not reveal the classic features of multicystic dysplasia of the kidney.

–Radionuclide scan is useful in estimating the function of the involved kidney.

–Technetium-99m (99mTc) mercaptoacetyltriglycine (MAG-3) and 99mTc dimercaptosuccinic acid (DMSA) studies can demonstrate lack of function in the affected kidney, but MAG-3 and DTPA studies can also provide information regarding drainage in an obstructed hydronephrotic kidney.

–The hydronephrotic form of MCDK can mimic ureteropelvic junction obstruction, and radionuclide scanning is necessary to confirm the diagnosis.

–On radionuclide scan, the area of the MCDK appear as a photopenic region that represents displaced tissue with background activity only.

–DMSA renal scanning demonstrates absence of function in the kidney with multicystic dysplastic kidney.

•Voiding cystourethrography (VCUG):

–This is useful in patients with MCDK to evaluate for vesicoureteral reflux (VUR).

–VUR could lead to reflux nephropathy in the contralateral solitary kidney.

–Current recommendations for patients with unilateral multicystic dysplastic kidney include evaluation of the contralateral kidney for VUR by VCUG.

–VUR has been reported in 4–19 % of contralateral kidneys but it is usually low grade and resolves in early life.

–VCUG may be deferred, unless abnormal ultrasonography findings in the contralateral kidney or ureter and/or a history of UTI are noted.

•Intravenous pyelography (IVP):

–This is not usually necessary; however, if multicystic dysplastic kidney involves only the upper or lower segment of a duplicated system, an IVP might reveal a small but functional ipsilateral kidney with an incomplete and possibly dilated calyceal system.

•Abdominal CT-scan is also rarely done to diagnose MCDK (Figs. 5.12, 5.13, 5.14, 5.15, and 5.16).

–Abdominal CT-scan show the typical multicystic appearance of MCDK with little or no parenchyma. Cyst wall calcification may be seen also.

–If a contrast-enhanced CT scan is performed, there is no excretion seen.

•Retrograde pyelography is rarely done to demonstrate an atretic or absent ureter. This is usually done through a cystoscope.

–Retrograde pyelography demonstrates a ureter that terminates blindly below the ureteropelvic junction.

•Abdominal MRI:

–This show the typical multicystic appearance of MCDK with little or no parenchyma.

5.10Treatment

•In the past, nephrectomy was often performed to establish the diagnosis.

•Currently, the role of nephrectomy in multicystic dysplasia of the kidney (MCDK) is controversial.

•The indications for nephrectomy in multicystic dysplasia of the kidney are:

–Large multicystic dysplastic kidney causing abdominal or flank pain

–Urinary tract infection (UTI)

–Hypertension

–Renal malignancy

•Multicystic dysplasia of the kidney can attain a large size and cause significant abdominal or flank discomfort and pain and these should be removed.

•Urinary tract infection involving the multicystic dysplastic kidney calls for its removal.

•Multicystic dysplastic kidney complicated by hypertension is an indication for nephrectomy.

•The presence of a renal malignancy based on diagnostic imaging is an indication for nephrectomy.

–Some concern surrounds the possibility that the intervening stroma of a kidney

affected by multicystic dysplastic kidney might provide a focus for malignant degeneration.

–No increased risk of Wilms tumor has been demonstrated in patients with multicystic dysplastic kidney.

–Some authors recommend nephrectomy only in patients who do not show involution