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In recent years, progress has been made on understanding the relationship between vesicoureteral reflux (VUR) and urinary tract infection (UTI). The findings on recent prospective, randomized, controlled studies have questioned the conventional VUR clinical significance and, therefore, have challenged the traditional diagnostic and therapeutic recommendations. These new studies have redefined the pathogenic role of vesicoureteral reflux in UTI as well as have disputed the routine use of urinary antibiotic prophylaxis to prevent UTI and renal damage in VUR patients. The time to overinvestigate and treat the vast majority of otherwise healthy children who have an uncomplicated UTI with long-term antibiotic prophylaxis seems to be over. Is there a role of severe VUR in the development of chronic renal disease and renal failure? New ideas are needed to answer these questions with the goal to avoid repeating past mistakes when therapeutic choices were based on expert opinions rather than facts.

Background: Premature and/or intrauterine growth-restricted neonates have an increased risk of developing postnatal renal injuries in later life. Studies on renal physiology in these neonates at a corrected age of 30-40 days are scarce and mostly relate to preterm infants. The data from these studies often lack the results of correlation analyses between biochemical parameters and nephron number-data which could provide additional insight and/or improve recognition of individuals at higher risk of renal failure., Methods: Urinary total protein and albumin levels and N-acetyl-β-D-glucosaminidase and cathepsin B activity were evaluated in preterm and intrauterine growth-restricted infants at a corrected age of 30-40 days and compared to data from a healthy control neonate population. The data were then associated with predominant susceptibility factors of renal damage related to low nephron number, such as gestational age, birth weight, total renal volume and renal cortex volume., Results: Compared to the control neonate population, we found significantly increased levels of all biochemical parameters tested in the intrauterine growth-restricted neonates, whereas in the preterm infants we observed a significant increase in cathepsin B activity, total protein level and, to a lesser extent, albumin level. Cathepsin B activity showed a significant, strong and inverse correlation with all surrogate markers of nephron number and was also strongly and positively correlated with urinary albumin level., Conclusions: At this postnatal age, we found that lower nephron number in low birth weight neonates was associated to tubular impairment/injury that could be concurrent with a dysfunction of glomerular permeability. Urinary cathepsin B activity may be a candidate marker for the early prediction of renal susceptibility to damage in low birth weight neonates.

Purpose: To examine the incidence of secondary primary malignancies in patients with renal cortical neoplasms., Methods: Between January 1989 and July 2010, 3647 patients underwent surgery at our institution for a renal cortical neoplasm and were followed through 2012. Occurrence of other malignancies was classified as antecedent, synchronous, or subsequent. All patients with antecedent malignancies (n = 498) and a randomly selected half of those with synchronous malignancies (n = 83) were excluded. The expected number of second primaries was calculated by multiplying Surveillance, Epidemiology, and End Results Program incidence rates of renal cortical neoplasms by person-years at risk within categories of age, sex, and year of diagnosis. The standardized incidence ratio (SIR) was calculated as observed cancers divided by expected incidence of the cancer, with approximation to the exact Poisson test used to obtain confidence intervals (CI) and p values., Results: Of 3066 patients with renal cortical neoplasms, 267 had a second primary cancer; the five most common in men were prostate, colorectal, bladder, lung, and non-Hodgkin's lymphoma; the five most common in women were breast, colorectal, lung, endometrium, and thyroid. Men demonstrated higher than expected thyroid cancer rate (SIR 5.0; 95 % CI 1.83-10.88, p = 0.002), and women had higher than expected rates of stomach cancer (SIR 5.0; 95 % CI 1.61-11.67, p = 0.004) and thyroid cancer (SIR 4.62; 95 % CI 1.69-10.05, p = 0.003)., Conclusions: The incidence of certain types of second malignancies may be higher in patients after diagnosis of renal cortical neoplasms compared to the general population. These observations can inform clinical follow-up in kidney cancer survivorship and future research studies., Competing Interests: The authors declare that they have no conflict of interest.

The mitotic arrest deficient protein MAD2B is a well-defined anaphase-promoting complex/cyclosome (APC/C) inhibitor and a small subunit of DNA polymerase zeta. It is critical for mitotic control and DNA repair. However, the pathological role of MAD2B in kidney diseases has not been fully elucidated. In the present study, we aim to explore the role of MAD2B in the pathogenesis of renal tubulointerstitial fibrosis (TIF) and the underlying mechanism. By immunofluorescence and immunohistochemistry, we found an obvious MAD2B enhancement in tubular area of TIF patients and unilateral ureteral obstruction (UUO) mice. In vitro, transforming growth factor-β1 (TGF-β1) induced a time-dependent MAD2B accumulation prior to tubular epithelial-to-mesenchymal transition (EMT) in a rat proximal tubular epithelial cell line, NRK-52E. Knocking down MAD2B using siRNA dramatically inhibited TGF-β1-induced tubular EMT process and subsequent extracellular matrix (ECM) production. We also found that Skp2, a confirmed APC/C-CDH1 substrate and E-cadherin destroyer, was increased in TGF-β1-treated proximal tubular epithelial cells, which could be blocked by MAD2B depletion. In addition, Skp2 expression was also found to be increased in the renal tubular area of UUO mice. Locally knocking down MAD2B expression in the renal cortex using lentiviral transfection inhibited Skp2 expression, tubular EMT, and subsequent ECM accumulation. Taken together, our data suggests a pro-fibrotic role of MAD2B in the pathogenesis of tubular EMT and TIF by inducing Skp2 expression. MAD2B might be a potential target of promising interventions for renal TIF., Key Messages: Renal fibrosis activates MAD2B expression in renal tubules of human and mouse. TGF-β1 contributes to MAD2B enhancement in rat tubular epithelial cells. MAD2B depletion alleviates renal tubulointerstitial fibrosis in vivo and in vitro. MAD2B promotes EMT transition in rat tubular epithelial cells by inducing Skp2.

Objective: To compare imaging findings with histopathology in AML without visible fat (AMLwvf)., Material and Methods: With IRB approval, we identified 18 AMLwvf that underwent CT between 2002-2014. A radiologist measured NECT-attenuation, corticomedullary (CM) and nephrographic (NG) enhancement, echogenicity relative to renal cortex (RC) (N = 5), T2W (T2AML/T2RC) signal-intensity (SI), and chemical-shift SI ([SIIN-PHASE - SIOPPOSED-PHASE]/SIIN-PHASE) indices (N = 6). A pathologist re-evaluated 15/18 AMLwvf for 1) < or > 25% adipocytes/high-power-field (HPF), 2) "many or few" blood vessels. Comparisons were performed using chi-square and independent t-tests., Results: 73.3%(11/15) of AMLwvf had <25% adipocytes/HPF and 86.7%(13/15) had "many" blood vessels. NECT-attenuation was 41.8(±6.9) HU. 61.1 %(11/18) of AMLwvf were hyper-attenuating and 38.9%(7/18) iso-attenuating; attenuation was associated with %-adipocytes/HPF, (p = 0.01). CM/NG enhancement were 63.3(±20.8)/51.7(±15.5) HU. 72.2%(13/18) of AMLwvf had wash-out enhancement, with no association with amount of blood vessels at pathology, (p = 0.68). No difference in echogenicity was noted by histology (p > 0.05). All AMLwvf were T2-hypointense (SI ratio = 0.61 [±0.1]). 2/6 AMLwvf showed SI drop on chemical-shift MRI; both were iso-attenuating and were associated with >25% adipocytes/HPF (p = 0.04)., Conclusions: AMLwvf are typically T2-hypointense and hyper-attenuating with wash-out enhancement due to abundant smooth muscle and vessels respectively. Iso-attenuating AMLwvf with microscopic fat on MRI contain more adipocytes/HPF., Key Points: • Five percent of AML do not demonstrate detectable fat on imaging • These AML are hyperattenuating and T2-hypointense due to abundant smooth muscle • These AML show washout enhancement without association to vessel count at histopathology • Iso-attenuating AML with microscopic fat on MRI show >25% adipocytes/HPF • The term "AML without visible fat" is proposed to reduce ambiguity.

Objective: To evaluate perinatal body organ apparent diffusion coefficient (ADC) values at postmortem magnetic resonance imaging (PMMR) in order to evaluate postmortem changes., Methods: Postmortem diffusion-weighted imaging (DWI) of the thorax and abdomen were performed with diffusion gradient values b = 0, 500, and 1000 s/mm(2) on 15 foetal and childhood cases (mean 33.3 ± 7.8 weeks gestation) compared to 44 live infants (mean age 75.5 ± 53.4 days). Mean ADC values were calculated from regions of interest (ROIs) for the lungs, liver, spleen and renal cortex, compared to normative live infantile body ADC values of similar gestational age., Results: Mean ADC values were significantly lower in postmortem cases than in normal controls for liver (0.88 10(-3) mm(2)/s ± SD 0.39 vs. 1.13 ± 0.13; p < 0.05) and renal cortex (0.85 ± 0.26 vs. 1.19 ± 0.13; p < 0.05) but not spleen or muscle. Mean lung ADC values were significantly higher than normal controls (1.06 ± 0.18 vs. 0 ± 0; p < 0.001), and there was a significant correlation between postmortem interval and lung ADC (R(2) = 0.55)., Conclusion: Lung PMMR ADC values are related to postmortem interval, making them a potential marker of time since death. Further research is needed to understand the organ-specific changes which occur in the postmortem period., Key Points: • Liver and spleen PM ADC values were lower than controls. • Lung ADC changes correlate with PM interval. • These findings may be useful in medicolegal cases.

Objective: Our objective was to evaluate pathological and functional changes in chronic kidney disease (CKD) using diffusion tensor imaging (DTI) at 3 T., Methods: There were fifty-one patients with CKD who required biopsy and 19 healthy volunteers who were examined using DTI at 3 T. The mean values of fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) were obtained from the renal parenchyma (cortex and medulla). Correlations between imaging results and the estimated glomerular filtration rate (eGFR), as well as pathological damage (glomerular lesion and tubulointerstitial injury), were evaluated., Results: The renal cortical FA was significantly lower than the medullary in both normal and affected kidneys (p < 0.001). The parenchymal FA was significantly lower in patients than healthy controls, regardless of whether eGFR was reduced. There were positive correlations between eGFR and FA (cortex, r = 0.689, p = 0.000; and medulla, r = 0.696, p = 0.000), and between eGFR and ADC (cortex, r = 0.310, p = 0.017; and medulla, r = 0.356, p = 0.010). Negative correlations were found between FA and the glomerular lesion (cortex, r = -0.499, p = 0.000; and medulla, r = -0.530, p = 0.000), and between FA and tubulointerstitial injury (cortex, r = -0.631, p = 0.000; and medulla, r = -0.724, p = 0.000)., Conclusion: DTI is valuable for noninvasive assessment of renal function and pathology in patients with CKD. A decrease in FA could identify the glomerular lesions, tubulointerstitial injuries, and eGFR.

Objectives: To investigate whether DTI allows assessment of renal impairment and pathology in patients with chronic glomerulonephritis., Materials and Methods: Seventy-five patients and 20 healthy volunteers were enrolled in this study. Renal function and kidney biopsies were evaluated. For DTI, a respiratory-triggered coronal EPI sequence was performed (TR, 1400 ms; TE, 76 ms; diffusion direction, 6; NEX, 4; b values, 0 and 600 s/mm2; slices thickness, 6 mm, with no intersection gap). Renal ADC and FA values were calculated and compared between the groups. Correlations between ADC/FA and histopathology were evaluated., Results: ADC values decreased with increased stages. ADC differences in renal parenchyma at different disease stages were found, with the exception of the control group compared with stage 1 patients; similar results were obtained for FA. ADC values in the cortex and medulla in stage 1-3 patients were both statistically different, similar to the FA values. A significant negative correlation was found between the percentage of glomerulosclerosis and FA in the renal cortex (r =  -0.74), similar to the degree of tubulointerstitial fibrosis with FA in the medulla (r = -0.76)., Conclusions: ADC and FA values are correlated with the degree of renal impairment, the percentage of glomerulosclerosis, and area of interstitial fibrosis., Key Points: • DTI can be used to assess renal function impairment in patients with chronic glomerulonephritis. • ADC and FA values were correlated with tubulointerstitial fibrosis and glomerulosclerosis. • Identification of renal impairment is helpful for timely treatment. • DTI can be used for non-invasive assessment of renal pathology.

Objectives: To compare sodium ((23)Na) characteristics between native and transplanted kidneys using dual-tuned proton ((1)H)/sodium MRI., Methods: Six healthy volunteers and six renal transplant patients (3 normal function, 3 acute allograft rejection) were included. Proton/sodium MRI was obtained at 3 T using a dual-tuned coil. Signal to noise ratio (SNR), sodium concentration ([(23)Na]) and cortico-medullary sodium gradient (CMSG) were measured. Reproducibility of [(23)Na] measurement was also tested. SNR, [(23)Na] and CMSG of the native and transplanted kidneys were compared., Results: Proton and sodium images of kidneys were successfully acquired. SNR and [(23)Na] measurements of the native kidneys were reproducible at two different sessions. [(23)Na] and CMSG of the transplanted kidneys was significantly lower than those of the native kidneys: 153.5 ± 11.9 vs. 192.9 ± 9.6 mM (P = 0.002) and 8.9 ± 1.5 vs. 10.5 ± 0.9 mM/mm (P = 0.041), respectively. [(23)Na] and CMSG of the transplanted kidneys with normal function vs. acute rejection were not statistically different., Conclusions: Sodium quantification of kidneys was reliably performed using proton/sodium MRI. [(23)Na] and CMSG of the transplanted kidneys were lower than those of the native kidneys, but without a statistically significant difference between patients with or without renal allograft rejection., Key Points: Dual-tuned proton/sodium RF coil enables co-registered proton and sodium MRI. Structural and sodium biochemical property can be acquired by dual-tuned proton/sodium MRI. Sodium and sodium gradient of kidneys can be measured by dual-tuned MRI. Sodium concentration was lower in transplanted kidneys than in native kidneys. Sodium gradient of transplanted kidneys was lower than for native kidneys.

Objective: To evaluate the feasibility of using magnetisation transfer (MT) MRI of the kidney at 3.0 T to assess renal function., Methods: Forty-four patients who underwent abdominal MRI on a 3.0-T system including gradient-echo (GRE) sequences with and without MT pulse were included. In each patient, MT ratio (MTR) of the renal cortex and medulla was measured by using regions of interest (ROIs) placed on the MTR map image., Results: Regression analysis showed good correlation between estimated glomerular filtration rate (eGFR) and MTR of the renal cortex (r = -0.645, P < 0.0001). Among 44 patients, 22 were categorised as the normal renal function group and 22 were classified as the decreased eGFR group. The mean MTR of the renal cortex in patients with decreased eGFR (mean MTR, 30.7 ± 3.2 %) was significantly higher (P < 0.0001) than that in patients with normal renal function (mean MTR, 25.3 ± 2.2 %), although the mean MTRs of the renal medulla in the two groups were not significantly different., Conclusion: There was good correlation between eGFR and MTR of the renal cortex derived from MT MRI at 3.0 T. This technique may have the potential to evaluate the degree of renal function non-invasively in patients with renal impairment., Key Points: • Magnetisation transfer techniques can provide new information about renal disease. • MTR values of the renal cortex correlate well with estimated glomerular filtration. • Higher MTR of the renal cortex exists in patients with renal dysfunction. • MT MRI at 3.0 T may be useful for evaluating renal function.

Intrauterine growth retardation is presumed to be associated with decreased renal size and impaired renal function as a result of stunted kidney development and nephron deficit. To study whether very preterm birth also affects renal size at young adulthood, we sonographically measured bipolar kidney length and volume in 51 very premature individuals (<32 weeks of gestation), either small (SGA) or appropriate (AGA) for gestational age (22 SGA and 29 AGA), and 30 full-term controls 20 years after birth. Relative kidney length and volume were calculated. Both absolute and relative left kidney length and volume were significantly lower in SGA and AGA individuals, notably in women. Renal size did not differ between SGA and AGA individuals. In 70% of controls, the left kidney was larger than the right one compared with 40.9% in SGA [relative risk (RR) 1.7; 95% confidence interval (CI) 1.0-3.0] and 48.3% in AGA (RR 1.5; 95% CI 0.9-2.3) individuals. Renal structural anomalies were present in eight prematurely born participants only. Our data suggest that kidney growth is stunted after preterm birth, especially on the left side, and in the female gender.

Caveolae are plasma membrane invaginations that contain a variety of signal transduction molecules and receptors for growth factors and cytokines. This study was performed to examine the in vivo expression and localization of caveolin-1 in kidneys from 19 children who underwent surgery release of ureteropelvic junction obstruction (UPJO) in relation to renal function and degree of tubulointerstitial fibrosis. Renal biopsies were carried out at the time of surgery for obstruction release. Kidney tissue from children of similar age removed because of carcinoma was used as control. Expression of caveolin-1 at the protein level in renal tissue and urine was demonstrated in patients with technetium 99 m labeled diethylene triamine pentaacetate ((99)Tc DTPA) renal scan 28.8+/-2% and increased tubular interstitial fibrosis in seven patients at the time of obstruction release. Colocalization staining of AT(1) angiotensin II receptor with caveolin-1 in basolateral membrane of epithelial tubule cells, enhanced AT(1) messenger ribonucleic acid (mRNA) and decreased endothelial nitric oxide synthase (eNOS), were shown in these patients. In contrast, absence of association of caveolin-1 with AT(1) receptor expression in proximal and collecting tubule membranes with AT(1) receptor mRNA and eNOS mRNA expression near control were demonstrated in 12 patients, with (99)Tc DTPA renal scan 39.7+2.1% and no evidence of tubulointerstitial fibrosis. From our results, the role of caveolin-1 as a factor contributing to the severity of the tubulointerstitial process resulting from obstructive nephropathy could be suggested.

Acute renal failure (ARF) is an uncommon but alarming complication of idiopathic nephrotic syndrome. The renal failure could be secondary to causes evident from the history and evaluation, such as severe intravascular volume depletion, acute tubular necrosis, allergic interstitial nephritis, bilateral renal vein thrombosis, acute pyelonephritis, or rapid progression of the original glomerular disease. It may be termed idiopathic if the underlying cause is undetermined. We present three children with idiopathic nephrotic syndrome who were admitted with acute renal failure. One case was due to drug-induced allergic interstitial nephritis. The other two were idiopathic in nature. Improvement in renal function occurred in the three patients over a variable period of 10 days to 4 weeks. After careful exclusion of well-known causes of acute renal failure, idiopathic acute renal failure (IARF) should be considered as a diagnostic possibility in these patients. The exact pathophysiology of IARF is not understood. Possible proposed explanations include interstitial edema, tubular obstruction, altered glomerular permeability, and unrecognized hypovolemia.

Previous studies have indicated that a combined trisomy of chromosomes 7 and 17 is a constant finding in papillary renal cortical adenomas and that papillary renal cell carcinomas are marked by additional trisomies such as trisomy 12, 16, and 20. The aim of our study was to compare this cytogenetic classification of papillary renal cortical tumors with conventional histopathologic classification. We performed interphase cytogenetics with enumeration probes for chromosomes 7, 12, 16, 17, and 20 on 41 papillary tumors found in 21 nephrectomy and 10 autopsy kidneys. A total of 38 tumors harbored gains of chromosomes 7 or 17, and most of these showed a trisomic signal distribution. The three tumors with normal copy numbers for chromosomes 7 and 17 were a papillary grade-2 carcinoma, a small adenoma (both with distinctive oxyphilic cytoplasm), and a papillary carcinoma with focally clear cells. Gains for chromosomes 12, 16, or 20 were found in 21 tumors and were significantly associated with the presence of histologic criteria of malignancy ( P<0.0001). Histopathologic and cytogenetic features of malignancy were found in eight tumors smaller than 10 mm. There is a good agreement of cytogenetic and histopathologic criteria of malignancy in papillary renal cell tumors. Interphase cytogenetics might give useful additional information in cases of doubt or when only small biopsy specimens are available.

Renal medullary carcinoma is a recently described tumor that occurs exclusively in patients with sickle cell trait. Although extremely rare, the distinctive demographic, clinical, and radiologic findings should suggest the diagnosis of this aggressive neoplasm.

Studies have suggested that glomerular size increases in childhood minimal lesion with age or growth. To examine whether mean glomerular volume (MGV) of pediatric patients with focal segmental glomerulosclerosis (FSGS) also increases with age and whether FSGS by itself can contribute to glomerular hypertrophy, we studied 67 children (40 boys, 27 girls) with primary FSGS and 95 children (68 boys, 27 girls) with minimal lesion by morphometry. FSGS patients had segmental sclerosis affecting 17.1% +/- 14.8% of the glomeruli. The percentage of segmental glomerulosclerosis was not related to age. MGV increased with age in the FSGS patients (r2 = 0.36, P < 0.001) and in the minimal lesion patients (r2 = 0.37, P < 0.001). MGV of children with FSGS is significantly larger than that of the minimal lesion group [(14.8 +/- 5.7) x 10(5) microm3 vs. (12.1 +/- 3.7) x 10(5) microm3, P < 0.001]. Multiple regression estimates suggest that the FSGS lesion affects MGV independently (P < 0.001). The volume density of mesangium and the volume density of cortical interstitium were significantly greater in the FSGS patients than in the minimal lesion patients (P < 0.001). These results indicate that MGV of pediatric FSGS patients increases with age and that the FSGS lesion itself may cause glomerular hypertrophy, possibly via mesangial expansion. Thus, glomerular hypertrophy in childhood minimal lesion may be an indicator of FSGS that is undetected because of the problem of sampling.

We describe a case of renal leiomyoma in a 21-year-old woman who presented with flank pain and hematuria. Urographic and computed tomographic (CT) studies revealed a large right renal mass with polypoid outgrowth protruding into the renal pelvis. Cortical renal leiomyoma with this radiographic manifestation is extremely rare.

We report two patients with methylmalonic acidemia (MMA) in whom renal biopsy demonstrated interstitial nephritis, bringing the total of such reported cases to four. In addition, hypertension, observed in one of our patients, has not been previously reported as the presentation of renal disease in MMA. The etiology of interstitial nephritis in MMA did not appear to be due to urate nephropathy. To date, 15 patients with MMA have been reported with renal complications, including chronic renal failure, making it imperative that children with MMA have their renal status evaluated.

We reviewed histologically 86 nephrectomy specimens from patients with vesicoureteral reflux (with or without ureterovesical obstruction) to investigate the relationship between coexisting hypoplasia and postnatally acquired cortical damage. Hypoplasia was assessed independently of the acquired cortical loss using medullary ray glomerular counting. Severe hypoplasia (glomerular number < 25% of normal) was detected in 47 of 86 patients. These patients underwent nephrectomy at a significantly younger age than those with minimal or no hypoplasia (P < 0.01). There was no significant relationship between the severity of hypoplasia and the presence or absence of obstruction. Severe acquired cortical loss was found in 68 of 86 patients. There was no significant association between the severity of cortical loss and the presence or absence of obstruction, age at nephrectomy or degree of coexisting hypoplasia. The findings suggest a strong association of hypoplasia and vesicoureteral reflux. Therefore, early postnatal presentation with minimal renal function need not necessarily reflect a failure of management but rather a pre-existing limitation of renal capacity. Furthermore, in a significant proportion of fetuses with ultrasonographic evidence of urinary tract abnormality, renal pathology may be present prior to the time at which in utero surgical intervention may be considered.

Acute renal cortical necrosis is a rare cause of acute renal failure that is usually associated with third trimester obstetrical complications. The appearance of this condition on contrast-enhanced computed tomography (CT) has rarely been described. A case of acute cortical renal necrosis is presented and the findings on contrast-enhanced CT are described. The pathologic correlation is also presented.

In addition to the triad in the Hermansky-Pudlak syndrome (tyrosine-positive oculocutaneous albinism, mild bleeding tendency with a normal platelet-count and widespread accumulation of ceroid-like pigment in various organs), we document severe pulmonary fibrosis, pseudomelanosis coli and deeply pigmented renal cortex. In the liver, innumerable number of pigment-laden Kupffer cells and macrophages in the Glisson capsule were seen. Interestingly, many intralysosomal accumulations of the pigment within the hepatocytes were found by electron microscopy, suggesting that these configurations possibly resulted from a dysfunction of the lysosome itself, especially with regard to loss of digestive and secretory activity. The triad and other complications may also be resultants of a lysosomal dysfunction.

The fine structural details of how leukocytes appear in the lumen of tubules and the localization of bacteria in the tubulo-interstitial space were studied by light and electronmicroscopy in renal cortical biopsy specimens from three patients with acute pyelonephritis. The cells of interstitial infiltrates infiltrated and sometimes disrupted the cortical collecting tubules preferentially, while inflammatory infiltration of the proximal and distal convoluted tubules occurred more rarely. Since the emigration of tubular wall-localized individual leukocytes into the lumen was not observed even in long series of thin sections, focal inflammatory disruption of the uriniferous ducts was considered to be the morphological basis of the intratubular accumulation of leukocytes. The structural simplicity of the collecting tubular cells is suggested to be the reason for their preferential involvement in the drainage of the interstitial suppuration, although a role for specific carbohydrate receptors cannot be excluded. The bacteria were usually found within the neutrophilic granulocytes and macrophages of the interstitial infiltrates, and within and among the cells of leukocyte casts. Additionally, pure bacterial colonies were noticed in the lumen of a few collecting tubules. The problem of the adherence of the bacteria to the surface of the tubular cells is discussed.

Over a 15-year period we observed seven children (four girls, three boys) who presented within the first months of life with severe renal failure and acidosis, associated with hypertension in five patients and polyuria in four. In addition, one patient had a severe cholestatic liver disease. In two families, a similarly affected sibling had died previously. Four patients were referred with the clinical diagnosis of polycystic kidney disease because of moderate enlargement of kidneys, but renal imaging (intravenous pyelography and ultrasonography) did not confirm this diagnosis. A renal biopsy, performed in all patients, showed similar features characterized by a diffuse chronic tubulo-interstitial nephritis (TIN) and particularly by the presence of microcystic dilatation of proximal tubules and Bowman's space. Liver pathology was normal in two patients, including one with hepatomegaly. However, in the patient with cholestasis there was inflammatory portal fibrosis with mild duct proliferation. Progression of the renal disease was extremely rapid and all patients reached end-stage renal failure (ESRF) before the age of 2 years (11-22 months). Two children had successful renal transplants. Although this chronic TIN shares some features with nephronophthisis, we suggest that it represents a distinct entity both on clinical and morphological grounds. The specific clinical features of this disease are its early onset and rapid progression to ESRF. Pathologically, it differs from nephronophthisis by the absence of medullary cysts and thickened tubular basement membranes and by the presence of cortical microcysts.

In order to define sonographic criteria for acute rejection of renal allografts, the following sonographic criteria were evaluated: (a) parenchymal thickness, (b) index of maximal sagittal to maximal longitudinal diameter, (c) cortical echos, (d) sinus echo changes, and (e) the medullary pyramids. Thirteen kidneys were removed for rejection. All had ultrasound studies 24 hours preoperatively. The sonographic changes in rejected kidneys were compared to those in 21 normal allografts. We found that renal enlargement, enlarged medullary pyramids, and a reduction in or a disappearance of the sinus echos were seen in acute rejection but were not seen in normal renal transplants. We conclude that these criteria are early signs of acute rejection and may be helpful in diagnosis, particularly if control sonograms are available.

Ninety-eight patients with lupus nephritis followed up for 3 years or more since initial biopsy were the subject of a qualitative and quantitative study of interstitial lesions. Thirty of the 98 patients showed interstitial cell infiltration and/or fibrosis. The initial and final creatinine clearance (Ccr) values were significantly lower in these 30 patients than in the remaining cases. Hypertension and progressive cases were more frequent in the group with interstitial lesions. Histologically, the severity and activity of glomerular lesions and IgG deposition in tubular basement membranes were more severe in the interstitial disease group. On a quantitative analysis of interstitial volumes (IV) in 20 of the 30 patients, there were significant differences in delta IV between the two respective groups with Ccr values greater than 80 ml/min and with those less than 80 both at the initial and final observations (p less than 0.05, each). Further, renal function was significantly lower in 11 cases showing delta IV greater than 17%, than in 9 cases with less than this (p less than 0.01). However, no differences in delta IV were found between the two groups divided according to the degree of severity and activity of glomerular lesions. Further, there was no correlation between renal function, and the severity and activity of glomerular lesions in the 20 cases with interstitial lesions. These results indicate that quantitative analysis is a very useful tool in the evaluation of the functional and prognostic significance of interstitial alterations in lupus nephritis.

A new technique for performing renal biopsy using ultrasonic real-time guidance was developed at our clinic in 1978. The puncture procedure is monitored in 2-dimensional real-time images by a mechanical sector scanner equipped with an attachment for needle guidance. The technique is called "selective renal biopsy" because tissue can be obtained selectively from any portion of the kidney. During the last 4 years, 150 such procedures have been performed on 148 patients. The success rate has been 96%. No serious complications occurred.

A diagnosis of paroxysmal nocturnal hemoglobinuria may be suggested with magnetic resonance imaging, based on the massive renal cortical hemosiderosis that occurs in this disease. A diffuse bilateral depression of renal cortical signal intensity will be observed that is caused mainly by a shortening of the T2 relaxation time of renal cortical protons by the paramagnetic effect of the locally increased ferric ion concentration in the proximal convoluted tubule.