ystic kidney diseases are being diagnosed earlier and earlier (1) because of more accessible routine prenatal US and advances in US technology. However, differential diagnosis often remains a challenge because kidney cysts can arise in a large variety of illnesses, imaging patterns evolve over time, and extrarenal features of systemic diseases may not be present at a young age. Thus, imaging findings for a particular disease in newborns may be different from those in adolescents, and predicting prognosis or deciding on optimal follow-up intervals can be challenging. Imaging can contribute not only to accurate diagnosis and prognosis but also to rational management of cystic nephropathies. In adults with autosomal dominant polycystic kidney disease (ADPKD), for example, total kidney volume measured at MRI has emerged as a useful tool with which to identify patients who will benefit from treatment (2); however, transfer and adaptation of these findings to children is still an important research need. The purpose of this consensus statement is to establish uniform standards for choosing the correct imaging modality and diagnostic criteria for the most common cystic kidney diseases in childhood and adolescence and to propose rational approaches to diagnosis and follow-up in important clinical settings. The spectrum of diseases covered here includes simple cysts; multicystic dysplastic kidneys (MCDKs); cystic dysplasia and HNF1B-associated disease; autosomal recessive polycystic kidney disease (ARPKD) and ADPKD; other ciliopathies, such as nephronophthisis and Bardet-Biedl syndrome; acquired cystic kidney disease

Objectives To identify important factors in the differential diagnosis of renal cysts associated with hyperechogenic kidneys. Methods

The aim of the study was to determine whether a urinary tract appearing normal when assessed by meticulous ultrasound (US) examination may coexist with vesicoureteric reflux (VUR) and whether a normal US scan can be used to exclude VUR, thereby avoiding unnecessary voiding cystourethrography (VCUG). The US features of 35 neonates with known VUR were reviewed. Criteria studied included pelvic dilatation above 7 mm on a transverse scan, calyceal or ureteral dilatation, pelvic or ureteral wall thickening, absence of the corticomedullary differentiation (CMD) and signs of renal dysplasia (small kidney, thinned or hyperechoic cortex and cortical cysts); all signs that have been shown to result from or to be associated with VUR. 57 refluxing renal units (RRU) were found among the 35 patients. VUR was bilateral in 22. Among the 57 RRU, at least one US anomaly that would have prompted VCUG was present in 50 (87.7%). Pelvic dilatation above 7 mm was present in 29 RRU (50.9%) only. Calyceal dilatation was present in 24 RRU, the dilatation involving the calyces but not the renal pelvis in seven. Ureteral dilatation was observed in 15 RRU. Pelvic or ureteral wall thickening was present in seven RRU. CMD was absent in 32 RRU (56.1%). US signs of dysplasia were found in 19 RRU. No US anomaly was found in seven RRU (12.3%) in six patients. A careful and meticulous US examination of the neonatal urinary tract allows the detection of over 87% of RRU by showing at least one sonographic abnormality. It is concluded that a normal appearing urinary tract on US does not usually coexist with VUR and that in such cases VCUG is not necessary.

Objective To determine whether a specific prenatal sonographic pattern can be identified for autosomal dominant polycystic kidney disease (ADPKD)

The authors report a new method of diagnosing hyaline membrane disease (HMD) in newborns: ultrasound. Babies with HMD display a specific pattern with retrohepatic hyperechogenicity on abdominal ultrasound. The specificity of the pattern was verified in 40 prematures with respiratory distress syndrome. The sign was present in 24, and in 22 of these the final diagnosis was moderate or marked HMD. In the last 2, mild HMD was suggested. The pattern was absent in the 16 others, none of whom had HMD. The pattern probably results from an ultrasound artifact: summation of multiple aerated airways surrounded by collapsed alveoli. Follow-up examinations were possible in 13 babies with HMD. Hyperechogenicity disappeared in 8 of these patients within 6-9 days and in 3 within 10-20 days; it persisted for 60 and 70 days in 2 with bronchopulmonary dysplasia. In conclusion, retrohepatic hyperechogenicity in newborns is pathognomonic for HMD and allows an instant diagnosis. The persistence of the pattern could be a useful criterion for evaluation of the prognosis.