Medullary sponge kidney in childhood

Proteomic Analysis of Urinary Extracellular Vesicles Reveals a Role for the Complement System in Medullary Sponge Kidney Disease

Medullary sponge kidney (MSK) disease is a rare and neglected kidney condition often associated with nephrocalcinosis/nephrolithiasis and cystic anomalies in the precalyceal ducts. Little is known about the pathogenesis of this disease, so we addressed the knowledge gap using a proteomics approach. The protein content of microvesicles/exosomes isolated from urine of 15 MSK and 15 idiopathic calcium nephrolithiasis (ICN) patients was investigated by mass spectrometry, followed by weighted gene co-expression network analysis, support vector machine (SVM) learning, and partial least squares discriminant analysis (PLS-DA) to select the most discriminative proteins. Proteomic data were verified by ELISA. We identified 2998 proteins in total, 1764 (58.9%) of which were present in both vesicle types in both diseases. Among the MSK samples, only 65 (2.2%) and 137 (4.6%) proteins were exclusively found in the microvesicles and exosomes, respectively. Similarly, among the ICN samples, only 75 (2.5%) and 94 (3.1%) proteins were exclusively found in the microvesicles and exosomes, respectively. SVM learning and PLS-DA revealed a core panel of 20 proteins that distinguished extracellular vesicles representing each clinical condition with an accuracy of 100%. Among them, three exosome proteins involved in the lectin complement pathway maximized the discrimination between MSK and ICN: Ficolin 1, Mannan-binding lectin serine protease 2, and Complement component 4-binding protein β. ELISA confirmed the proteomic results. Our data show that the complement pathway is involved in the MSK, revealing a new range of potential therapeutic targets and early diagnostic biomarkers.

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.

Efficacy of Multi-Detector Computed Tomography for the Diagnosis of Medullary Sponge Kidney

Objective

To expand the diagnostic armamentarium for medullary sponge kidney (MSK), we evaluate the use of high-resolution multidetector computed tomography (MDCT) for MSK diagnosis and compare to the standard intravenous urography (IVU). Despite a significant prevalence amongst stone formers, diagnosis of this well described condition has declined. IVU, the gold standard in MSK diagnosis, has largely been replaced by CT, which has previously been shown unable to demonstrate signs of MSK.

Methods and Materials

Patients with known history of MSK based on IVU underwent limited MDCT urogram. Control group patients, without MSK, also had MDCT urograms performed for other clinically indicated conditions. Studies were scored by board-certified radiologists on a 0-2 scale based on the likelihood of MSK. IVU studies, when available, were similarly graded.

Results

MDCT was diagnostic of MSK in 9 out of the 10 patients with known history of MSK. No false positives were present in our series. The one case of MSK not detected on MDCT was graded as a "1" on its respective IVU. Sensitivity and specificity were 90 and 100%, respectively, when compared with IVU.

Conclusion

Concordance with IVU findings, despite a small reduction in sensitivity, indicates MDCT to be a suitable, and more readily available replacement for IVU in the diagnosis of MSK.

[Imaging of medullary sponge kidney: notes for urologists]

The medullary sponge kidney is a malformation characterized by Bellini ducts' ectasias and often by nephrocalcinosis. Scientific literature demonstrates and emphasizes how the Rx-urography plays a primary role to achieve diagnostic certainty in cases of suspected MSK. Pathognomonic urographic aspects in cases of medullary sponge kidney are defined as "bouquet of flowers", "bunch of grapes" or "brush". None of the other methods of imaging available today has the same diagnostic accuracy.

Medullary sponge kidney: state of the art

Medullary sponge kidney (MSK) is a kidney malformation that generally manifests with nephrocalcinosis and recurrent renal stones; other signs may be renal acidification and concentration defects, and pre-calyceal duct ectasias. MSK is generally considered a sporadic disorder, but an apparently autosomal dominant inheritance has also been observed. As MSK reveals abnormalities in both the lower and the upper nephron and is often associated with urinary tract developmental anomalies, its pathogenesis should probably be sought in one of the numerous steps characterizing renal morphogenesis. Given the key role of the GDNF-RET interaction in kidney and urinary tract development and nephrogenesis, anomalies in these molecules are reasonable candidates for explaining a disorder such as MSK. As a matter of fact, we detected two, hitherto unknown, rare variants of the GDNF gene in MSK patients. We surmise that a defective distal acidification has a central role in MSK and is followed by a chain of events including defective bone mineralization, hypercalciuria, hypocitraturia and stone formation.

Medullary sponge kidney presenting in a neonate with distal renal tubular acidosis and failure to thrive: a case report

Introduction

Medullary sponge kidney is a congenital anomaly characterized by diffuse ectasy of the collecting tubules of one or both kidneys. It is usually diagnosed in the second or third decade of life.

Case presentation

Distal renal tubular acidosis is commonly observed in patients with medullary sponge kidney. We describe here a 50-day-old Egyptian Caucasian girl with medullary sponge kidney who had features of distal renal tubular acidosis, (persistent alkaline urine, hypercalciuria, hypocitraturia) and failure to thrive. Renal ultrasound revealed left renal increased medullary echogenicity and bilateral nephrocalcinosis.

Conclusion

Early gene(s) expression of medullary sponge kidney disease might be responsible for persistent metabolic acidosis during the neonatal period.

Medullary sponge kidney associated with multivessel fibromuscular dysplasia: report of a case with renovascular hypertension

Medullary sponge kidney (MSK) is a congenital anomaly characterized by dilatation of the collecting ducts of Bellini associated with defective urinary acidification and concentration. Medullary nephrocalcinosis/ nephrolithiasis is the usual presentation in adults, however neonatal and childhood cases are being reported with increasing frequency. Among the conditions associated with MSK are Beckwith-Wiedemann syndrome/hemihyperplasia (13%), horseshoe kidney, congenital small kidney, hyperparathyroidism, Caroli syndrome, congenital hepatic fibrosis, Ehlers-Danlos syndrome, Marfan syndrome, immotile cilia syndrome, and arterial fibromuscular dysplasia. This article describes an adult female who underwent nephrectomy for renovascular hypertension due to multivessel fibromuscular dysplasia with small left kidney found to be associated with MSK.

Medullary sponge kidney (Lenarduzzi–Cacchi–Ricci disease): A Padua Medical School discovery in the 1930s

The introduction of radiological contrast media and intravenous (i.v.) urography in clinical diagnostics in the 1930s enabled the discovery of several diseases, including the medullary sponge kidney (MSK). MSK is a renal malformation characterized by cystic anomalies of precalyceal ducts, which is frequently associated with nephrocalcinosis and renal stones. Although it was first recognized by G Lenarduzzi in 1939, its thorough description was the result of the ante litteram multidisciplinary cooperation between a radiologist (Lenarduzzi), a urologist (Cacchi), and a pathologist (Ricci), all at the Padua University Hospital. These authors 'established' the paradigm for its diagnosis that is still used today. I.v. urography is the gold standard for the diagnosis of MSK, but as the technique is used less and less, there is a concrete possibility of this renal condition being forgotten in the future. Although the pathogenesis of MSK has yet to be elucidated, its association with different malformative conditions supports the idea that it is a developmental disorder. Recent findings suggest that MSK may be the consequence of a disruption of the ureteral-bud/metanephric-blastema interface.

Medullary sponge kidney

Medullary sponge kidney is a benign asymptomatic developmental anomaly of the kidney mostly seen in adult females. Presentation in childhood is uncommon. Urinary tract infection, nephrolithiasis, hematuria and hypercalciuria are the common complications. We report a eleven-year-old female child who presented with recurrent urinary tract infection and nephrolithiasis and was found to have bilateral medullary sponge kidney.

Causes of increased renal medullary echogenicity in Turkish children

The primary disorders of 50 children with increased renal medullary echogenicity on renal ultrasound were studied; 28 girls and 22 boys aged from 1 month to 16 years were classified into four groups based on underlying disease and ultrasound findings. Group 1 was composed of 17 patients with distal renal tubular acidosis (34%); intense echoes throughout the pyramid were predominant. Group 2 consisted of 14 patients with vitamin D toxicity (28%) and an intense echogenic rim around the pyramids. Group 3 included 10 patients with different types of tubulopathies. A slight hyperechogenic rim around the sides and tip of the medullary pyramids was detected. Group 4 was made up of 9 patients with rare underlying conditions. Abdominal X-rays detected medullary calcinosis in only 12 (24%) of the total 50 patients. Ultrasonography appears to be an important tool in the early diagnosis of increased renal medullary echogenicity and medullary nephrocalcinosis.

Nephrocalcinosis in a child with autosomal dominant polycystic kidney disease and a prolapsing ectopic ureterocele

Although autosomal dominant polycystic kidney disease commonly presents in adults, it can occur in children. Usually, renal calcification in patients with autosomal dominant polycystic kidney disease is manifested as calculi or as hemorrhage into a renal cyst. An ectopic ureterocele is a well-known finding in patients with renal duplication. To our knowledge, this is the first case report of a child who had combined findings of autosomal dominant polycystic kidney disease, nephrocalcinosis, and an obstructing ectopic ureterocele.

Renal cystic disease in infants and children

Renal cystic disease is a common abnormality of the kidney in the pediatric age group. Cystic disease may occur as a sporadic dysplasia or, somewhat more commonly, represent a genetic disorder. Establishment of an accurate diagnosis, prognosis, and treatment requires a broad approach to the problem, including radiologic imaging, renal function testing, and occasionally surgical biopsy. Interpretation of the imaging studies requires understanding of the patterns of renal cystic disease in the pediatric age group.

Medullary sponge kidney on axial computed tomography: comparison with excretory urography

To evaluate features of medullary sponge kidney (MSK) on computed tomography (CT), 4-mm-thick axial slices without intravenous contrast material were first made in 13 patients through 24 kidneys which showed images of MSK on excretory urograms. On CT, papillary calcifications were found in eleven kidneys. In five of these kidneys, the calcifications were not detectable on plain films. Some hyperdense papillae (attenuation value 55-70 Hounsfield units) without calcification were found in four other kidneys. Nine kidneys appeared normal. Ten of these 24 kidneys were reexamined by a second series of 4-mm-thick axial slices, 5 min after intravenous injections of 50 ml of Urografin. Images suggesting possible ectasia of precaliceal tubules were found in only four kidneys. These images appear much less obvious and characteristic on CT than on excretory urogram and do nothing more than suggest the possibility of MSK. In conclusion, the sensitivity of CT in the detection of MSK is markedly lower than that of excretory urography. In the most florid cases of the disease, CT can only show images suggesting the possibility of MSK. On the other hand, CT appears much more sensitive than plain films and tomograms of excretory urography in the detection of papillary calcifications, the most frequent complication of MSK.

Pyramidal hyperechogenicity in autosomal recessive polycystic kidney disease resembling medullary nephrocalcinosis

Striking pyramidal hyperechogenicity resembling the sonographic appearance of medullary nephrocalcinosis was found in autosomal recessive polycystic kidney disease (ARPKD). This sonographic pattern is distinctly different from those described previously in ARPKD.

Segmental medullary sponge kidney mimicking a renal mass

We report an unusual case of a medullary sponge kidney that presented clinically and radiologically as a renal mass. Histopathological study after nephrectomy proved the mass to be consistent with segmental medullary sponge kidney.

CT visualization of medullary sponge kidney

Recognizing the changes of medullary sponge kidney (MSK) on computed tomographic (CT) scans may be of value in both diagnosis and in differentiating this from other disease states. The appearance on CT of MSK has not previously been well described. A case is reported that demonstrates ectatic renal collecting tubules visualized by CT, and techniques are suggested to optimize visualization of these changes.

Renal dysgenesis and cystic disease of the kidney: a report of the Committee on Terminology, Nomenclature and Classification, Section on Urology, American Academy of Pediatrics

We believe that the confusion regarding abnormal renal development could be reduced by more precise terminology. Therefore, we suggest precise definitions for dysgenesis, hypoplasia, dysplasia, hypodysplasia, aplasia and agenesis of the kidney. We suggest the term reflux nephropathy be a generic label for any instance of abnormal renal morphology (gross or microscopic) associated with vesicoureteral reflux. Hypoplasia and hypodysplasia can be subclassified on the basis of associated urological criteria. There have been many previous attempts to classify cystic disease of the kidney but none has been accepted collectively by pathologists, urologists, nephrologists and radiologists. On the basis of known patterns of inheritance, a classification is outlined in which renal cystic disease is divided into 2 major groups: genetic and nongenetic. Each entity is discussed.