High-Resolution Renal Sonography in Children with Autosomal Recessive Polycystic Kidney Disease

Reversed cortico-medullary differentiation in the fetal and neonatal kidneys: an indicator of poor prognosis?

BACKGROUND

Bilateral reversed cortico-medullary differentiation is rarely observed on fetal or neonatal renal ultrasound and is therefore a diagnostic challenge.

OBJECTIVE

Our purpose was to widen the differential diagnoses of fetal and neonatal nephropathies introducing reversed cortico-medullary differentiation as a clue either on obstetric US or during follow-up of hyperechoic kidneys in order to improve the management of such rare clinical situations.

MATERIALS AND METHODS

We retrospectively reviewed the US images of 11 patients showing bilateral reversed cortico-medullary differentiation on prenatal examination or in which this pattern developed postnatally in the follow-up of fetal hyperechoic kidneys. For each patient, a precise diagnosis was established either on clinical assessment or, when available, on histological or genetic findings.

RESULTS

Six fetuses displayed bilateral reversed cortico-medullary differentiation on obstetric examination, and the pattern persisted throughout pregnancy. In the five other fetuses, the kidneys appeared initially homogeneously hyperechoic; this evolved into reversed cortico-medullary differentiation during the third trimester in two cases and shortly after birth in three cases. Two pregnancies were terminated because of estimated poor prognosis. In the nine surviving neonates, four died of renal failure in the post-natal period. The clinical evolution was more favorable in the remaining five newborns.

CONCLUSIONS

Six different diagnoses were established in patients presenting with a reversed cortico-medullary differentiation renal pattern. This finding was associated with poor outcome in six cases. An acute prenatal diagnosis of reversed cortico-medullary differentiation improves pre- and postnatal work-up and guides counseling and genetic testing.

Localized cystic disease of the kidney in pediatric patients: Clinical and imaging findings with long term follow up

INTRODUCTION

This study aimed to describe the clinical and imaging findings, including ultrasonography (US) findings, and long-term follow-up results in pediatric patients with localized cystic disease of the kidney (LCDK).

MATERIAL AND METHODS

Retrospective review of pediatric patients diagnosed with LCDK based on imaging findings showing multiple localized renal cysts with intervening normal renal parenchyma from January 2002 to August 2020. Clinical presentations and US features of the affected and contralateral kidneys were reviewed and compared with computed tomography or magnetic resonance imaging findings, if available.

RESULTS

A total of 18 patients (male:female = 11:7; median age, 8 years) were included. Initial clinical presentations were incidental findings (n = 5), abdominal pain (n = 5), or hematuria (n = 5). Of the seven patients (7/18, 39%) who showed multiple hyperechoic foci with ring-down artifacts within the cystic lesions on US, six patients showed focal calcification of the cysts on CT. Two patients (2/18, 11%) had milimetric cysts in the contralateral kidney. During follow-up (range, 2-122 months), there was an increase in lesion size, with ipsilateral renal growth in four patients (4/18, 22%). There was no renal function impairment at the initial presentation or during follow-up in all patients.

CONCLUSIONS

LCDK can present with milimetric calcifications (39%), contralateral milimetric renal cysts (11%), and mild size increase during renal growth (22%) in children without renal function impairment. Follow-up US is recommended without surgical intervention in these typical cases.

Prevalence, risk factors and disease knowledge of polycystic kidney disease in Pakistan

Polycystic kidneys disease refers to cyst(s) formation in kidneys with severe consequences of end stage renal disease thus have higher mortality. It is a common genetic disease occurring either as autosomal dominant polycystic kidney (ADPKD) or autosomal recessive polycystic kidney disease (ARPKD) with prevalence rates of 1/1000 and 1/40,000 respectively. Dominant forms presenting in later (>30) while recessive in earlier ages (infancy) and affecting both sexes and almost all race. The patient experiences many renal as well as extra-renal manifestations with marked hypertension and cyst formation in other organs predominantly in liver. Due to genetic basis, positive family history is considered as major risk factor. Ultrasonography remains the main stay of diagnosis along with family history, by indicating increased renal size and architectural modifications. Initially disease remains asymptomatic, later on symptomatic treatment is suggested with surgical interventions like cyst decortications or drainage. Dialysis proved to be beneficial in end stage renal disease. However renal transplantation is the treatment of choice.

Pediatric cystic diseases of the kidney

Pediatric renal cystic diseases include a variety of hereditary or non-hereditary conditions. Numerous classifications exist and new data are continuously published. Ultrasound is the primary technique for evaluating kidneys in children: conventional and high-resolution US allows a detailed visualization of renal parenchyma and of number, size and location of the cysts, hence representing the most important diagnostic imaging technique for the first diagnosis and follow-up of these young patients. The purpose of this pictorial essay is to review the spectrum of renal cystic lesions in children from simple, complex or malignant single cysts to the several poly/multicystic kidney diseases.

Hereditary Renal Cystic Disorders: Imaging of the Kidneys and Beyond

The purpose of this article is to review the hereditary renal cystic diseases that can manifest in children and adults, with specific attention to pathogenesis and imaging features. Various common and uncommon hereditary renal cystic diseases are reviewed in terms of their underlying etiology, including the involved genetic mutations and the affected proteins and cellular structures. Focus is placed on the morphologic findings in each condition and the features that distinguish one disorder from another. The two most common categories of hereditary renal cystic disease are (a) the ciliopathic disorders, which are related to mutations affecting the primary cilia (called "ciliopathies"), and (b) the phakomatoses. Autosomal dominant polycystic kidney disease, autosomal recessive polycystic kidney disease, and the "medullary cystic disease complex" are all ciliopathies but have different phenotypes. Tuberous sclerosis complex and the associated "contiguous gene syndrome," as well as von Hippel-Lindau syndrome, are phakomatoses that can manifest with cystic renal lesions but have uniquely different extrarenal manifestations. Finally, DICER1 mutations can manifest with renal cystic lesions (typically, cystic nephromas) in patients predisposed to other malignancies in the chest, ovaries, and thyroid. Although some overlap exists in the appearance of the renal cysts associated with each of these diseases, there are clear morphologic differences (eg, cyst size, location, and complexity) that are emphasized in this review. To improve patient outcomes, it is important for the radiologist to recognize the various hereditary renal cystic diseases so that a correct diagnosis is assigned and so that the patient is adequately evaluated and followed up. ^©RSNA, 2017.

From the radiologic pathology archives: pediatric polycystic kidney disease and other ciliopathies: radiologic-pathologic correlation

Genetic defects of cilia cause a wide range of diseases, collectively known as ciliopathies. Primary, or nonmotile, cilia function as sensory organelles involved in the regulation of cell growth, differentiation, and homeostasis. Cilia are present in nearly every cell in the body and mutations of genes encoding ciliary proteins affect multiple organs, including the kidneys, liver, pancreas, retina, central nervous system (CNS), and skeletal system. Genetic mutations causing ciliary dysfunction result in a large number of heterogeneous phenotypes that can manifest with a variety of overlapping abnormalities in multiple organ systems. Renal manifestations of ciliopathies are the most common abnormalities and include collecting duct dilatation and cyst formation in autosomal recessive polycystic kidney disease (ARPKD), cyst formation anywhere in the nephron in autosomal dominant polycystic kidney disease (ADPKD), and tubulointerstitial fibrosis in nephronophthisis, as well as in several CNS and skeletal malformation syndromes. Hepatic disease is another common manifestation of ciliopathies, ranging from duct dilatation and cyst formation in ARPKD and ADPKD to periportal fibrosis in ARPKD and several malformation syndromes. The unifying molecular pathogenesis of this emerging class of disorders explains the overlap of abnormalities in disparate organ systems and links diseases of widely varied clinical features. It is important for radiologists to be able to recognize the multisystem manifestations of these syndromes, as imaging plays an important role in diagnosis and follow-up of affected patients.

Autosomal recessive polycystic kidney disease: antenatal diagnosis and histopathological correlation

Autosomal recessive polycystic kidney disease (ARPKD) is one of the most common inheritable disease manifesting in infancy and childhood with a frequency of 1:6,000 to 1:55,000 births. The patient in her second trimester presented with a history of amenorrhea. Ultrasound examination revealed bilateral, enlarged, hyperechogenic kidneys, placentomegaly, and severe oligohydramnios. The pregnancy was terminated. An autopsy was performed on the fetus. Both the kidneys were found to be enlarged and the cut surface showed numerous cysts. The liver sections showed changes due to fibrosis. The final diagnosis of autosomal recessive polycystic kidney disease was made based on these findings. In this article, we correlate the ante-natal ultrasound and histopathological findings in autosomal recessive polycystic kidney disease.

Clinical and pathological features of a neonate with autosomal recessive polycystic kidney disease caused by a nonsense PKHD1 mutation

BACKGROUND

Autosomal recessive polycystic kidney disease (ARPKD) is one of the most common hereditary nephropathies in childhood. We report a neonate with ARPKD presenting with oligohydramnios, enlargement and increased echogenicity of both kidneys shown by antenatal sonograms after a 29-week gestation and died within the first few hours of life.

METHODS

The neonate was investigated pathologically post-mortem. PCR-DNA direct sequencing was performed to detect the exons of the PKHD1 gene for mutation analysis.

RESULTS

Autopsy findings of the kidney and liver confirmed the diagnostic hypothesis. PKHD1 mutation analysis revealed that there was a homozygous nonsense mutation c.9319C>T (p.R3107X), which was found to be pathogenic, in exon 58 in the neonate.

CONCLUSIONS

The recurrence of PKHD1 mutation c.9319C>T (p.R3107X) in the ARPKD population might be a good evidence that it is disease associated. Given the limitations of antenatal ultrasound, PKHD1 mutation analysis is helpful for accurate genetic counseling and early prenatal diagnosis.

Postnatal imaging of neonates with prenatally diagnosed genitourinary abnormalities: a practical approach

The advent of prenatal US and, more recently, fetal MRI has changed our pattern of referrals. In the current clinical algorithms, most neonates evaluated for genitourinary abnormalities are asymptomatic. These infants are referred for multidisciplinary consultation, imaging and surveillance. Evaluation of these children commences following pertinent review of available prenatal studies; this is appropriate, as in certain instances prenatally gathered information of potential prognostic significance can be inferred or can obviate the need for multiple examinations. US remains the first-line imaging modality for diagnosing urinary abnormalities in neonates and young infants, although it offers primarily morphological assessment. However, US coupled with MAG-3 scanning results in a powerful combination that provides anatomical and functional information. Recently, MRI and MR urography have been increasingly regarded as one-stop-shop examinations that can deliver both anatomical and functional information, and play an increasing role in the evaluation of ureteral ectopia and genital anomalies. Fluoroscopic examinations are reserved to exclude vesicoureteral reflux, to delineate urethral obstruction or to provide additional information to support a diagnosis. A practical approach to postnatal imaging of the neonate is discussed and the important genitourinary anomalies in this age group are presented and illustrated.

Pleuropulmonary blastoma in a child with autosomal-recessive polycystic kidney disease

Autosomal-recessive polycystic kidney disease (ARPKD) is a developmental disorder known to affect both the kidneys and the liver. Renal involvement results in progressive renal insufficiency and hypertension, while hepatic involvement can result in portal hypertension and cholangitis. Pulmonary abnormalities relate mainly to pulmonary insufficiency in those patients who present as neonates. We present a unique case of a child with ARPKD found to have a cystic lesion of the lung. Upon surgical resection, a pathological diagnosis of pleuropulmonary blastoma (PPB) was made. There are no previous reports in the literature describing the association of these two entities. Knowledge of this potential association is important in the clinical management of these children and may open new avenues of genetic research.

Diagnosis and management of childhood polycystic kidney disease

A number of syndromic disorders have renal cysts as a component of their phenotypes. These disorders can generally be distinguished from autosomal dominant polycystic kidney disease (ADPKD) and autosomal recessive polycystic kidney disease (ARPKD) by imaging studies of their characteristic, predominantly non-renal associated abnormalities. Therefore, a major distinction in the differential diagnosis of enlarge echogenic kidneys is delineating ARPKD from ADPKD. ADPKD and ARPKD can be diagnosed by imaging the kidney with ultrasound, computed tomography, or magnetic resonance imaging (MRI), although ultrasound is still the method of choice for diagnosis in utero and in young children due to ease of use, cost, and safety. Differences in ultrasound characteristics, the presence or absence of associated extrarenal abnormalities, and the screening of the parents >40 years of age usually allow the clinician to make an accurate diagnosis. Early diagnosis of ADPKD and ARPKD affords the opportunity for maximal anticipatory care (i.e. blood pressure control) and in the not-too-distant future, the opportunity to benefit from new therapies currently being developed. If results are equivocal, genetic testing is available for both ARPKD and ADPKD. Specialized centers are now offering preimplantation genetic diagnosis and in vitro fertilization for parents who have previously had a child with ARPKD. For ADPKD patients, a number of therapeutic interventions are currently in clinical trial and may soon be available.

Renal pyramids: focused sonography of normal and pathologic processes

In neonates and children, sonographic examinations of the renal pyramids may depict a spectrum of unique changes in echogenicity due to the effects of physiologic processes or a wide variety of pathologic processes that may affect the collecting ducts or interstitium of the pyramids. Focused sonographic evaluation of the pyramids with high-frequency transducers produces the most detailed images of the pyramids, revealing some appearances not previously reported, to the authors' knowledge. The authors highlight the clinical settings in which they have documented detailed changes in the echogenicity of the pyramids. The patterns of altered echogenicity alone may reflect a specific cause but in many instances are nonspecific, with clinical and biochemical correlation required to establish a more precise diagnosis. However, there is a lack of histologic data to completely explain the mechanism of many of these changes in echogenicity in all of the processes. As the authors have expanded their use of the focused sonographic technique, they have been able to depict altered echogenicity in the pyramids in greater numbers of children in whom an explanation for the changes is not always immediately apparent; for now, the cause must be considered idiopathic. More work is required to expand the use of this focused technique together with clinical, biochemical, and histologic correlation in an attempt to offer more complete explanations for the changes in echogenicity of the pyramids.

Renal cystic diseases in children: new concepts

This review highlights the changes that have occurred in the general approach to cystic renal diseases in children. For instance, genetic mutations at the level of the primary cilia are considered as the origin of many renal cystic diseases. Furthermore, these diseases are now included in the spectrum of the hepato-renal fibrocystic diseases. Imaging plays an important role as it helps to detect and characterize many of the cystic diseases based on a detailed sonographic analysis. The diagnosis can be achieved during fetal life or after birth. Hyperechoic kidneys and/or renal cysts are the main sonographic signs leading to such diagnosis. US is able to differentiate between recessive and dominant polycystic kidney diseases, hepatocyte nuclear factor 1 Beta mutation, glomerulocystic kidneys and nephronophtisis. MR imaging can, in selected cases, provide additional information including the progressive associated hepatic changes.

Correlation of kidney function, volume and imaging findings, and PKHD1 mutations in 73 patients with autosomal recessive polycystic kidney disease

BACKGROUND AND OBJECTIVES

Renal function and imaging findings have not been comprehensively and prospectively characterized in a broad age range of patients with molecularly confirmed autosomal recessive polycystic kidney disease (ARPKD).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Ninety potential ARPKD patients were examined at the National Institutes of Health Clinical Center. Seventy-three fulfilled clinical diagnostic criteria, had at least one PKHD1 mutation, and were prospectively evaluated using magnetic resonance imaging (MRI), high-resolution ultrasonography (HR-USG), and measures of glomerular and tubular function.

RESULTS

Among 31 perinatally symptomatic patients, 25% required renal replacement therapy by age 11 years; among 42 patients who became symptomatic beyond 1 month (nonperinatal), 25% required kidney transplantation by age 32 years. Creatinine clearance (CrCl) for nonperinatal patients (103 +/- 54 ml/min/1.73 m(2)) was greater than for perinatal patients (62 +/- 33) (P = 0.002). Corticomedullary involvement on HR-USG was associated with a significantly worse mean CrCl (61 +/- 32) in comparison with medullary involvement only (131 +/- 46) (P < 0.0001). Among children with enlarged kidneys, volume correlated inversely with function, although with wide variability. Severity of PKHD1 mutations did not determine kidney size or function. In 35% of patients with medullary-only abnormalities, standard ultrasound was normal and the pathology was detectable with HR-USG.

CONCLUSIONS

In ARPKD, perinatal presentation and corticomedullary involvement are associated with faster progression of kidney disease. Mild ARPKD is best detected by HR-USG. Considerable variability occurs that is not explained by the type of PKHD1 mutation.

Autosomal recessive polycystic kidney disease and congenital hepatic fibrosis (ARPKD/CHF)

ARPKD/CHF is an inherited disease characterized by non-obstructive fusiform dilatation of the renal collecting ducts leading to enlarged spongiform kidneys and ductal plate malformation of the liver resulting in congenital hepatic fibrosis. ARPKD/CHF has a broad spectrum of clinical presentations involving the kidney and liver. Imaging plays an important role in the diagnosis and follow-up of ARPKD/CHF. Combined use of conventional and high-resolution US with MR cholangiography in ARPKD/CHF patients allows detailed definition of the extent of kidney and hepatobiliary manifestations without requiring ionizing radiation and contrast agents.

Segmental disorders of the nephron: histopathological and imaging perspective

Recent advances in molecular genetics and immunocytochemistry have clarified the cell of origin in many renal disorders. Several renal disorders are thought to involve specific segments of the nephron. Renin-secreting tumours arise from juxtaglomerular cells. Clear cell and papillary renal cell carcinoma (RCC) recapitulate the epithelium of the proximal tubules. Oncocytoma and chromophobe RCC differentiate towards Type A and Type B intercalated cells of the cortical collecting duct, respectively. Medullary collecting ducts are the target sites for the development of autosomal recessive polycystic kidney disease, collecting duct carcinoma and medullary carcinoma. Renal papillae are susceptible to unique changes such as necrosis or papillitis. The purpose of our article is threefold: to illustrate the imaging findings of renal disorders that show segmental involvement of the nephron, to describe proximal and distal nephron disorders and to correlate imaging findings of some entities with histopathological features.