Renal involvement in children with HNF1ß mutation: early sonographic appearances and long-term follow-up.

OBJECTIVES: The aim was to report ultrasound (US) patterns of hepatocyte nuclear factor (HNF1ß) mutation throughout childhood and determine whether ultrasound could be predictive of renal failure. METHODS: The sonographic examinations in 34 children with HNF1ß mutation were reviewed. Their sonographic characteristics were compared with renal function. RESULTS: At first postnatal examination renal length was normal in 44 % of the patients, decreased in 24 %, increased in 12 % and asymmetrical in 20 %. Renal cortex was hyperechoic in 97 %. Corticomedullary differentiation was abnormal in 59 %. Cysts were present in 77 % of patients. Cysts were mostly subcapsular (64 %). Twenty-eight patients had follow-up examinations. A modification of the sonographic appearance was observed in 91 % of patients. Eight patients (23 %) had renal failure; no specific US pattern could be demonstrated. CONCLUSIONS: At birth, HNF1ß mutation was typically associated on US with the combination of hyperechoic, normal-sized kidneys with abnormal corticomedullary differentiation (CMD) and multiple cortical cysts. In older children, the appearances can be variable: kidneys may have decreased (32 %) or normal size (33 %); they are usually hyperechoic (50 %) with abnormal CMD (78 %) and (sub)cortical cysts (71 %). No pattern appears to be associated with renal failure. KEY POINTS: • HNF1ß mutations determine significant anomalies of sonographic appearances of kidneys in children. • Kidneys appear mainly hyperechoic, with or without CMD and with subcapsular cysts. • The US pattern may evolve throughout childhood in the same patient. • No correlation was found between any sonographic pattern and renal failure.

Imaging and classification of congenital cystic renal diseases.

OBJECTIVE: The purpose of this clinical perspective is to describe a decision-tree approach to the finding of hyperechoic kidneys as signs of congenital renal cystic disease in fetuses and children. This approach takes into account the latest classification of inherited renal cystic diseases. The basis of the approach is a detailed sonographic analysis in addition to assessment of clinical data and the familial history. CONCLUSION: With the decision-tree approach, typical sonographic patterns can be described and used for accurate diagnosis of isolated renal cystic diseases and polymalformative syndromes. In some cases, however, the diagnosis is not achieved, and complementary examinations are needed.

A rare case of primary hyperoxaluria type 1 co-existing with autosomal-dominant polycystic kidney disease in a newborn.

We describe the first reported case to our knowledge of an infant presenting with the extremely rare association of primary hyperoxaluria type 1 (PH-1) and autosomal-dominant polycystic kidney disease (ADPKD). This diagnosis was suspected on the basis of the renal US findings and confirmed by complementary examinations. It led to severe oxalosis with very rapid onset of end-stage renal failure (ESRF) and required combined liver-kidney transplantation at the age of 18 months. The boy died 13 days after transplantation.

At what level of unilateral renal impairment does contralateral functional compensation occur?

Functional compensation occurs in a kidney when the function of the contralateral kidney is decreased or absent. What is, however, not documented is the level of unilateral renal impairment at which functional compensation occurs. Split function, as obtained from a radionuclide renogram, can only show the asymmetry between both kidneys. The aim of the present work was to evaluate at what level of unilateral impairment a functional compensation can be observed in the contralateral normal kidney. From a large database, 180 children over 2 years of age with unilateral pathology were retrospectively selected. All of them underwent a radionuclide study, combining a technetium-99m mercaptoacetyltriglycine (Tc-99m MAG3) renogram associated with a chromium-51 ethylenediaminetetraacetic acid (Cr-51 EDTA) overall clearance, allowing a precise estimation of single-kidney glomerular filtration rate (SKGFR). Below 30-35 ml/min/1.73 m2, there was a significant inverse correlation between SKGFR on the normal and the abnormal side. Above this level, no such correlation was observed, the mean SKGFR on the normal side remaining around 58 ml/min/1.73 m2, whatever the value of SKGFR on the abnormal side. In pediatric patients, hyperfunction occurs when SKGFR of the diseased kidney is below 30-35 ml/min/1.73 m2.

The contribution of ultrasound for the differential diagnosis of congenital and infantile nephrotic syndrome.

The aim of this study was to determine whether high-resolution ultrasound is able to differentiate between the various diseases associated with nephrotic syndrome (NS). We reviewed the US features of 15 patients less than 1 year presenting a NS whose exact type was defined by pathology nephrotic syndrome of Finnish type (NSFT, n=2); focal and segmental hyalinosis (FSH, n=3); minimal-change glomerular disease (MCGD, n=2); neonatal glomerulonephritis (n=1), and diffuse mesangial sclerosis (DMS, n=7). The US features studied included the size of the kidneys, cortical echogenicity, cortico-medullary differentiation (CMD), and borders. The images were reviewed on hard copies by two observers unaware of the final diagnosis. In each case a diagnosis was proposed based on the reading of the US features. Six patients with DMS displayed a peculiar US pattern: mild increase of renal size; and inhomogeneous (patchwork-like) parenchymal hyperechogenicity that included areas of the cortex and medulla. The NSFT and neonatal glomerulonephritis displayed some of the same US features: increased kidney size (+2 SD) and had homogeneous cortical hyperechogenity with persistent cortico-medullar differentiation. The kidneys in the 3 patients with SFH were sonographically normal (n=1) or displayed a mild cortical hyperechogenicity (n=2). Inhomogeneous parenchymal hyperechogenicity involving only segments of the cortex and medulla seems to be a specific US pattern for DMS. Ultrasound is less specific for the other types of CNS.