Multi-omic analysis of human kidney tissue identified medulla-specific gene expression patterns.

The kidney medulla is a specialized region with important homeostatic functions. It has been implicated in genetic and developmental disorders along with ischemic and drug-induced injuries. Despite its role in kidney function and disease, the medulla's baseline gene expression and epigenomic signatures have not been well described in the adult human kidney. Here we generated and analyzed gene expression (RNA-seq), chromatin accessibility (ATAC-seq), chromatin conformation (Hi-C) and spatial transcriptomic data from the adult human kidney cortex and medulla. Tissue samples were obtained from macroscopically dissected cortex and medulla of tumor-adjacent normal material in nephrectomy specimens from five male patients. We used these carefully annotated specimens to reassign incorrectly labeled samples in the larger public Genotype-Tissue Expression (GTEx) Project, and to extract meaningful medullary gene expression signatures. Using integrated analysis of gene expression, chromatin accessibility and conformation profiles, we found insights into medulla development and function and then validated this by spatial transcriptomics and immunohistochemistry. Thus, our datasets provide a valuable resource for functional annotation of variants from genome-wide association studies and are freely accessible through an epigenome browser portal.

Relationship between cortical and medullary thickness and glomerular filtration rate among living kidney donors.

The relationship between the kidney cortex and medulla is not well understood in healthy populations. This study characterised the relationship between cortical/medullary thickness and measured glomerular filtration rate (GFR) in 390 living kidney donors. A positive relationship was observed between medullary, but not cortical, thickness and GFR. We propose that this reflects a correlation between juxtamedullary nephron number and GFR.

G protein-coupled estrogen receptor 1 regulates renal endothelin-1 signaling system in a sex-specific manner.

Demographic studies reveal lower prevalence of hypertension among premenopausal females compared to age-matched males. The kidney plays a central role in the maintenance of sodium (Na+) homeostasis and consequently blood pressure. Renal endothelin-1 (ET-1) is a pro-natriuretic peptide that contributes to sex differences in blood pressure regulation and Na+ homeostasis. We recently showed that activation of renal medullary G protein-coupled estrogen receptor 1 (GPER1) promotes ET-1-dependent natriuresis in female, but not male, rats. We hypothesized that GPER1 upregulates the renal ET-1 signaling system in females, but not males. To test our hypothesis, we determined the effect of GPER1 deletion on ET-1 and its downstream effectors in the renal cortex, outer and inner medulla obtained from 12-16-week-old female and male mice. GPER1 knockout (KO) mice and wildtype (WT) littermates were implanted with telemetry transmitters for blood pressure assessment, and we used metabolic cages to determine urinary Na+ excretion. GPER1 deletion did not significantly affect 24-h mean arterial pressure (MAP) nor urinary Na+ excretion. However, GPER1 deletion decreased urinary ET-1 excretion in females but not males. Of note, female WT mice had greater urinary ET-1 excretion than male WT littermates, whereas no sex differences were observed in GPER1 KO mice. GPER1 deletion increased inner medullary ET-1 peptide content in both sexes but increased outer medullary ET-1 content in females only. Cortical ET-1 content increased in response to GPER1 deletion in both sexes. Furthermore, GPER1 deletion notably increased inner medullary ET receptor A (ETA) and decreased outer medullary ET receptor B (ETB) mRNA expression in male, but not female, mice. We conclude that GPER1 is required for greater ET-1 excretion in females. Our data suggest that GPER1 is an upstream regulator of renal medullary ET-1 production and ET receptor expression in a sex-specific manner. Overall, our study identifies the role of GPER1 as a sex-specific upstream regulator of the renal ET-1 system.

Automated Segmentation of Kidney Cortex and Medulla in CT Images: A Multisite Evaluation Study.

BACKGROUND: In kidney transplantation, a contrast CT scan is obtained in the donor candidate to detect subclinical pathology in the kidney. Recent work from the Aging Kidney Anatomy study has characterized kidney, cortex, and medulla volumes using a manual image-processing tool. However, this technique is time consuming and impractical for clinical care, and thus, these measurements are not obtained during donor evaluations. This study proposes a fully automated segmentation approach for measuring kidney, cortex, and medulla volumes. METHODS: A total of 1930 contrast-enhanced CT exams with reference standard manual segmentations from one institution were used to develop the algorithm. A convolutional neural network model was trained (n=1238) and validated (n=306), and then evaluated in a hold-out test set of reference standard segmentations (n=386). After the initial evaluation, the algorithm was further tested on datasets originating from two external sites (n=1226). RESULTS: The automated model was found to perform on par with manual segmentation, with errors similar to interobserver variability with manual segmentation. Compared with the reference standard, the automated approach achieved a Dice similarity metric of 0.94 (right cortex), 0.90 (right medulla), 0.94 (left cortex), and 0.90 (left medulla) in the test set. Similar performance was observed when the algorithm was applied on the two external datasets. CONCLUSIONS: A fully automated approach for measuring cortex and medullary volumes in CT images of the kidneys has been established. This method may prove useful for a wide range of clinical applications.

Direction of the Biopsy Needle in Ultrasound-Guided Renal Biopsy Impacts Specimen Adequacy and Risk of Bleeding.

INTRODUCTION: Although medical factors such as hypertension and coagulopathy have been identified that are associated with hemorrhage after renal biopsy, little is known about the role of technical factors. The purpose of our study was to examine the effects of biopsy needle direction on renal biopsy specimen adequacy and bleeding complications. METHODS: Two hundred and forty-two patients who had undergone ultrasound-guided renal biopsies were included. A printout of the ultrasound picture taken at the time of the biopsy was used to measure the biopsy angle ("angle of attack" [AOA]) and to determine if the biopsy needle was aimed at the upper or lower pole and if the medulla was targeted or avoided. RESULTS: Of the 3 groups of biopsy angle, an AOA of between 50°-70° yielded the most glomeruli per core (P = .001) and the fewest inadequate specimens (4% vs 15% for > 70°, and 9% for < 50°, P = .038). Biopsy directed at a pole vs an interpolar region resulted in fewer inadequate specimens (8% vs 23%, P = .005), while biopsies that were medulla-avoiding resulted in fewer inadequate specimens (5% vs 16%, P = .004) and markedly reduced bleeding complications (12% vs 46%, P < .001) compared to biopsies where the medulla was entered. DISCUSSION: An AOA of approximately 60°, aiming at the poles, and avoiding the medulla were each associated with fewer inadequate biopsies and bleeding complications. While biopsy of the medulla is necessary for some diagnoses, the increased bleeding risk emphasizes the need for communication between nephrologist, pathologist, and radiologist.

Multiparameter diffusion-weighted imaging for characterizing pathological patterns in lupus nephritis patients: A preliminary study.

BACKGROUND: Microstructural changes of lupus nephritis (LN) kidney such as inflammatory cell infiltration or fibrosis could influence water molecular movement or diffusion, which indicates that diffusion-weighted imaging (DWI) may become a valuable tool in evaluation of this disease. PURPOSE: To explore whether multiparameter diffusion-weighted imaging (mDWI) could contribute to characterize pathological patterns in LN patients. STUDY TYPE: Retrospective. POPULATION: Twenty-two patients with LN. FIELD STRENGTH/SEQUENCE: Multi-b value DWI was performed with a 3.0 T scanner. ASSESSMENT: Apparent diffusion coefficient (ADC)m , perfusion-related diffusion coefficient (Df ), molecular diffusion coefficient (Ds ), perfusion fraction (f), ADCs , α, ADCk , and mean kurtosis (MK) were calculated by monoexponential, biexponential, stretched-exponential, and kurtosis models fits, respectively. STATISTICAL TESTS: Independent sample t-test, Pearson analysis and receiver operating characteristic (ROC). RESULTS: In the whole group, the activity index (AI) correlated significantly with alpha values in the medulla (rho = -0.54, P = 0.03). The chronicity index (CI) correlated significantly with Ds values in the medulla (rho = -0.61, P = 0.02). No significant association was found between any other diffusion parameter and histologic grade with all P > 0.05. For differentiating proliferative LN (Class III or IV) from Class V, the area under the ROC curve (AUC) of alpha in the medulla was 0.833 (P = 0.023). DATA CONCLUSION: mDWI might be used for the characterization of pathological patterns in LN patients. LEVEL OF EVIDENCE: 3 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019;50:1075-1084.

Renal medullary carcinoma: a nearly fatal malignancy specifically affecting patients with a so-called benign condition.

Renal medullary carcinoma (RMC) is a highly aggressive and rare malignancy found almost exclusively in young patients with sickle cell trait (SCT). Metastatic disease is commonly present at diagnosis. There is very limited experience treating disseminated disease and the prognosis is dismal. We report the case of a young 9-year-old boy with SCT, who presented with 4 months' progression of abdominal pain, nausea and vomiting associated with cough spells, dysphagia, and weight loss. Upon evaluation, he was underweight, pale, and in mild respiratory distress. Cervical lymphadenopathy was evident and abdomen was diffusely tender. A whole-body CT scan showed a left kidney lesion with associated cervical, mediastinal, and retroperitoneal lymphadenopathy. Biopsy of a cervical lymph node revealed metastatic RMC. Patient was started on combination chemotherapy with paclitaxel, carboplatin, and gemcitabine followed by left adrenalectomy. In spite of having advanced disease, our patient achieved an excellent response with a progression-free survival of 17 months. Although SCT is thought to be a "benign" condition, RMC is one devastating complication associated with it. Considering its rarity, the near uniform associated fatality should prompt the question of whether clinical practice should change regarding proper counseling of these patients and raise awareness in the medical community.

The Concentration of Vanadium in Pathologically Altered Human Kidneys.

Vanadium has a unique and beneficial effect on both humans and animal organisms; however, excessive amount of the above-mentioned metal can cause many alterations in tissues and organs, including the kidneys. The aim of the study was to determine the concentration of vanadium (V) in the kidneys removed from patients due to lesions of various etiologies, including the rejection of the transplanted kidneys. Additionally, we determined the influence of selected biological and environmental factors on the V concentration. The study material consisted of the kidneys with tumor lesions (n = 27) and extracted kidney grafts (n = 10) obtained from patients from the north-western Poland. The V concentrations were assessed by atomic absorption spectrophotometry emission in inductively coupled argon plasma and expressed in concentrations in dry weight (dw). Statistically significant differences were observed for V concentrations in the renal medulla between the kidneys with tumors and renal grafts, where the lowest concentration of V was observed. The kidneys in more advanced stages of the tumor (T3 + T4) contained more vanadium than the kidneys of T1 + T2 stages and medians were 2.07 and 1.51, respectively. We also compared the V concentration in the kidneys between the renal grafts (K2) and the kidneys with tumor (K1) in two stages of advancement: T1 with T2 (K11 + 2) and T3 with T4 (K13 + 4). Statistically significant differences were noted between the renal medullae of the above-mentioned groups of kidneys.According to the previous studies on the concentrations of other heavy metals, renal grafts accumulate less vanadium than cancerous kidneys, what can be associated with the immunosuppressive drugs taken by patients after the transplantation.

A mathematical model of the rat kidney: K+-induced natriuresis.

A model of the rat nephron (Weinstein. Am J Physiol Renal Physiol 308: F1098-F1118, 2015) has been extended with addition of medullary vasculature. Blood vessels contain solutes from the nephron model, plus additional species from the model of Atherton et al. (Am J Physiol Renal Fluid Electrolyte Physiol 247: F61-F72, 1984), representing hemoglobin buffering. In contrast to prior models of the urine-concentrating mechanism, reflection coefficients for DVR are near zero. Model unknowns are initial proximal tubule pressures and flows, connecting tubule pressure, and medullary interstitial pressures and concentrations. The model predicts outer medullary (OM) interstitial gradients for Na+, K+, CO2, and [Formula: see text], such that at OM-IM junction, the respective concentrations relative to plasma are 1.2, 3.0, 2.7, and 8.0; within IM, there is high urea and low [Formula: see text], with concentration ratios of 11 and 0.5 near the papillary tip. Quantitative similarities are noted between K+ and urea handling (medullary delivery and permeabilities). The model K+ gradient is physiologic, and the urea gradient is steeper due to restriction of urea permeability to distal collecting duct. Nevertheless, the predicted urea gradient is less than expected, suggesting reconsideration of proposals of an unrecognized reabsorptive urea flux. When plasma K+ is increased from 5.0 to 5.5 mM, Na+ and K+ excretion increase 2.3- and 1.3-fold, respectively. The natriuresis derives from a 3.3% decrease in proximal Na+ reabsorption and occurs despite delivery-driven increases in Na+ reabsorption in distal segments; kaliuresis derives from a 30% increase in connecting tubule Na+ delivery. Thus this model favors the importance of proximal over distal events in K+-induced diuresis.

Application of time-spatial labeling inversion pulse in renal corticomedullary differentiation and time parameter optimization / 中国医学影像技术

Objective To investigate the application value of time-spatial labeling inversion pulse (T-SLIP) in renal corticomedullary differentiaton and the best black blood inversion time (BBTI) value.Methods Totally 60 volunteers were included,who underwent abdominal MR scan with noncontrast-enhanced SSFP sequence combined with T-SLIP.All subjects were scanned with different BBTI (800,1 000,1 200,1 400,1 600,1 800 ms) using coronary T-SLIP SSFP sequence.The images quality was evaluated using a four-point scale method.The region of renal cortex and medulla was devised automatically based on the image training algorithm.The signal intensity ratio with the different BBTI was calculated through measuring the signal intensity of the renal cortex and medulla.And the best BBTI values were analyzed.Results When BBTI was 1 200 ms,the image score was the highest.The signal intensity ratio (SIR) had statistical difference among different BBTI groups (all P＜0.05),when BBTI was 1 200 ms,the SIR was the highest,and the contrast between the renal cortex and medulla was obvious.Conclusion T-SLIP technology can improve the visibility of renal corticomedullary without contrast agents.The optimal BBTI for the best corticomedullary differentiation is 1 200 ms.

Topography, Composition and Structure of Incipient Randall Plaque at the Nanoscale Level.

PURPOSE: Randall identified calcium phosphate plaques in renal papillae as the origin of kidney stones. However, little is known about the early steps of Randall plaque formation preceding the onset of urolithiasis. Our objective was to characterize the composition and the initial formation site of incipient Randall plaque in nonstone forming, living patients. MATERIALS AND METHODS: Median patient age was 67.7 years. A total of 54 healthy papillae from kidneys removed for cancer and without stones were analyzed by immunohistochemistry and von Kossa staining, field emission-scanning electron microscopy with energy dispersive x-ray analysis, µ-Fourier transform infrared spectroscopy, cryo-transmission electron microscopy coupled to selected area electron diffraction and electron energy loss spectroscopy. RESULTS: Incipient Randall plaque was observed in 72.7% of kidneys. As expected, carbonated apatite was the main component of microcalcifications but amorphous calcium phosphate and whitlockite were identified in 80% and 40% of papillae, respectively. Incipient plaques were noted in the deepest part of the papillae around the loop of Henle tip as well as around the vasa recta, representing 62.4% and 37.2% of microcalcifications, respectively. Plaques were rarely close to collecting ducts. At the nanoscale level incipient calcifications were often composed of several nanocrystals in organic material that looked like microvesicles. CONCLUSIONS: Incipient Randall plaque is frequent. It appears not only at the extreme tip of the renal papillae around the hairpin structure of the loop of Henle but also around the vasa recta. Nanoscale analyses suggest a local nucleation process promoting nanocrystal growth in a supersaturated milieu. In addition, plaques contain various calcium and magnesium phosphates, and not only carbonated apatite.

Predicting Risk of Chronic Kidney Disease in Infants and Young Children at Diagnosis of Posterior Urethral Valves: Initial Ultrasound Kidney Characteristics and Validation of Parenchymal Area as Forecasters of Renal Reserve.

PURPOSE: There is paucity of validated objective early imaging markers to help predict future renal deterioration in infants with posterior urethral valves. We evaluated the prognostic value of total renal parenchymal area, renal echogenicity and corticomedullary differentiation regarding future development of chronic kidney disease. MATERIALS AND METHODS: We analyzed initial postnatal ultrasonographic images from serial posterior urethral valve cases seen at a single tertiary referral center using National Institutes of Health sponsored image processing software. Echogenicity and corticomedullary differentiation were objectively measured as ratios relative to the adjacent liver or spleen and between cortex and medulla. The primary study outcome, renal function at last followup, was dichotomized based on glomerular filtration rate and/or need for renal replacement therapy (dialysis or renal transplantation, stage 5 chronic kidney disease). RESULTS: A total of 75 patients were evaluated, of whom 16 had progression to stage 5 chronic kidney disease after a mean ± SD followup of 64.2 ± 38.9 months. Mean renal parenchymal area was 21.41 cm(2) in patients without and 16 cm(2) in patients with stage 5 chronic kidney disease (p <0.001), and mean corticomedullary differentiation was 1.77 and 1.21, respectively (p <0.001). Bilateral echogenic kidneys were significantly associated with development of stage 5 chronic kidney disease (p = 0.004). The performance of corticomedullary differentiation in predicting stage 5 chronic kidney disease was statistically significant (AUROC 0.881, 95% CI 0.776-0.987, p <0.001). CONCLUSIONS: Estimates of renal parenchyma quantity (total renal parenchymal area) and quality (corticomedullary differentiation and renal echogenicity) measured on initial postnatal ultrasound carry prognostic value in determining future risk of stage 5 chronic kidney disease in patients with posterior urethral valves. These data are promising for developing tools to risk stratify patients, counsel parents and customize monitoring protocols.

Assessment of the diffusion-weighted imaging for the pathology and renal function in IgA nephropathy / 天津医药

Objective To study the correlation between the diffusion-weighted imaging (DWI) measurements and glomerular filtration rate (GFR), Katafuchi scores in IgA nephropathy. Methods Thirty-five patients with IgA nephropathy (IgAN group) and twenty healthy volunteers (control group) were enrolled in this study. All of the subjects underwent bilateral renal DWI measurements with 3.0T MRI scanner. The values of apparent diffusion coefficient (ADC) of renal cortex and medulla were measured. GFR of IgAN group was detected with 99Tcm-DTPA scintigraphy. Based on the Lee classification and the Katafuchi score system, the pathological grading was carried out in patients of IgAN group. The ADC values were compared between control group and different grades of IgAN group. The correlations between ADC and GFR values were analysed in defferent groups. The correlations between ADC values and Katafuchi scores were analysed in IgAN group. Results The renal cortical ADC values were significantly higher than medulla ADC values in both control group and IgAN group (P 0.05). There was a positive correlation between the renal cortical and medulla ADC values and the GFR values in IgAN group (P medulla ADC values and the Katafuchi scores in IgAN group (P<0.05). Conclusion The diffusion-weighted imaging can reflect the physiological functions of kidney. It was feasible for application DWI in IgA nephropathy, which can be used for assessing the renal filtration function and the pathological damage. However, DWI measurement is not sensitive to early renal disease.

Medullary nephritis in the diagnosis of acute cellular rejection.

BACKGROUND: The purpose of this study was to understand the role of lymphomononuclear inflammation (nephritis) in the renal allograft medulla of transplant recipients with acute dysfunction, by comparing the immunophenotype of inflammatory cells present in the medulla and cortex of kidney graft biopsies. METHOD: This is a retrospective study of 113 renal allograft needle biopsies, presenting with medullary nephritis, divided into two groups according to the main location of nephritis: in cortical and medullary regions (corticomedullary nephritis) or exclusively in the medullary region (medullary nephritis). We performed immunohistochemistry (IHC) of the cells composing the inflammatory foci, using anti-CD4, CD8, CD20, CD68, and CD138 antibodies, respectively for T-helper cells, cytotoxic T cells, B lymphocytes, macrophages and plasmocytes. The clinical follow-up of the patients was correlated with the morphological findings. RESULTS: The nephritis was corticomedullary in 66 of the 113 cases (58.4%) and exclusively medullary in the remaining 47 cases (41.6%). The immunophenotype of the inflammatory cells was similar in the cortical and medullary compartments and were mainly: cytotoxic T lymphocytes (CD8) and macrophages CD68. The immunosuppressive therapeutic response to acute cellular rejection (ACR), based on decreasing of serum creatinine values, was 81.8% in the patients of the corticomedullary nephritis group and 63.6% in those of the medullary nephritis group. CONCLUSION: Medullary nephritis in renal allograft biopsies may indicate ACR, as could be noted by the immunophenotype, which presented the same cellular mediators of rejection seen in the allograft cortex, and by the positive immunosuppressive therapeutic response observed in most patients.

Hounsfield density of renal papillae in stone formers: analysis based on stone composition.

PURPOSE: We examined renal papillary Hounsfield density in stone formers with all common stone subtypes to further understand the pathophysiology of stone formation. MATERIALS AND METHODS: Using computerized tomography we measured the Hounsfield density of a 0.2 cm(2) renal papillary area in patients with a single renal calyceal stone. Results were compared with those in patients without a nephrolithiasis history who served as controls. Stone composition was determined by stone passage or extraction during endoscopic procedures using infrared spectroscopy and polarized microscopy. We measured the Hounsfield density of the stone bearing calyx and of a single calyx from the upper, middle and lower poles of each kidney. RESULTS: Mean ± SD renal papillary Hounsfield density in controls was 36.2 ± 4.0 HU. In patients with stones Hounsfield density was significantly greater than in controls in stone bearing calyces, nonstone bearing calyces in the affected kidney and calyces in the contralateral nonstone bearing kidney for all stone composition subtypes (range 48.4 to 61.3 HU, each p <0.001). CONCLUSIONS: Patients with kidney stones regardless of composition showed the unique radiographic characteristic of increased renal papillary Hounsfield density. This was true for all calyces and for each kidney in all stone formers with a single renal calyceal stone. This radiographic evidence supports the role of renal papillary deposits or plaques in the pathophysiology of stone formation.

Blood Oxygen Level Dependent MRI of Normal Kidney and Its Correlation with Physiological Indexes / 天津医药

Objective To explore the characteristics of blood oxygen level dependent (BOLD) magnetic resonance imaging (MRI) in healthy native kidneys. To investigate the relationship between BOLD-MRI and common physiological in-dexes. Methods GE 3.0T MRI scanner and Torsopa phased-array coil were employed to acquire renal coronal T1WI and BOLD image. Ninety patients who were ruled out chronic kidney diseases underwent BOLD-MRI with T2*-spoiled gradient recalled echo (T2*SPGR) sequence. BOLD images were analyzed on R2*map software. Cortical and medullary R2*values were analyzed in bilateral kidneys and in different gender. Different regional R2*values in cortex and medulla were also ana-lyzed. Physiological indices including age, body height and weight, body mass index (BMI), body surface area (BSA), estimat-ed glomerular filtration rate (eGFR) were recorded. Correlation between R2*value and physiological indices were analyzed. Results Bilateral renal cortical R2*values [left (16.56±1.40) Hz and right (16.66±1.28)Hz, respectively] were less than val-ues in medulla [left (28.82±3.71)Hz and right (28.36±3.72)Hz, respectively]. Female and male cortical R2*values [female (16.55±1.30Hz) and male (16.66±1.38)Hz, respectively] were also less than corresponding values in medulla [female (28.46± 3.64) Hz and male (28.70±3.78) Hz, respectively]. In bilateral renal medullary region, R2*values in low pole (27.29±3.05) Hz was less than values in middle (29.32±3.47) Hz and upper pole (29.16±4.21)Hz (F=15.184, P<0.001). Age was positive-ly correlated with R2* values in medulla (r =0.284, P =0.002). However, eGFR was negatively correlated with medullary R2*value (r=-0.232, P=0.007). Conclusion R2*values reflected the levels of renal partial pressure of oxygen and as-sessed the degree of renal ischemia. BOLD MRI could offer a simple, convenient and noninvasive method for to evaluate renal oxygen metabolism in cortex and medulla.

The 64-MSCT study of relationship between renal corticomedullary differentiation, contrast between renal cortex and medulla, renal cortex and medulla CT peak value with the single renal function in hydronephrotic kidney / 中华放射学杂志

valuating the unilateral renal function of hydronephresis.

Electron microscopic observation of Randall's plaque in patients with calcium oxalate stone / 中华泌尿外科杂志

Objective To study the ultrastructure of the renal papillary Randall's plaque in calclum oxalate stone formers. Methods The 14 biopsy samples of the Randall's plaque in 12 patients with calcium oxalate stone undergoing PCNL for stone removal were obtained using endoscopic biopsy technique,followed by staining with hematoxylin-eosin or fixing with osmium tetroxide,and then the ultrastructure of the Randall's plaque was observed under light microscope and transmission electron microscope. Results In all 12 patients,72 renal papillae were examined.All kidReys were found to have papillary plaque and 7 of the patients had attached stones.Sixty-three papillae(87.5%)contained plaque.Calcium deposition was seen in the 12 renal papilla tissue by light microscopy.Transmission electron microscopy images of the 2 Randall's plaque samples showed several cluster of sharp and large crystals lied closer to the surface of Randall's plaque.The typical crystals were acicular with light profile. Conclusions Randall's plaque is an interstitial medullary and papillary deposit of calcium oxalate.The appearance of the deposition of calcium oxalate crystals lies upon Randall's plaque,which might be an explanation for the mechanism of calcium oxalate stone formation.

Clinicopathological manifestations of nephronophthisis-medullary cystic kidney disease / 中华肾脏病杂志

Objective To report the clinicopathological features of 2 cases of nephronophthisis-medullary cystic kidney disease (NPH-MCKD). Methods The clinical data and pathological changes of renal biopsy in two patients of NPH-MCKD from our hospital were analyzed, and associated literatures were reviewed simultanously. The clinicopathological featuresand diagnosis of NPH-MCKD were discussed. Results Two adolescent patients were admitted to our hospital for indolent renal insufficiency, polyuria accompanied by polydipsia as first signs.Urine analysis showed low specific density urine, mild proteinuria, and few formed elements in urinary sediments. The ability of urine concentration and acidification was decreased. Familial history of renal disease and extra-renal lesions were not found. Renal ultrasound presented an increased echogenicity with diminished cortico-meduUary differentiation, and multiple small cysts in renal corticomedullary border were identified in one case by computed tomography. Pathological examination of renal biopsy revealed diffuse tubular interstitial lesion which was characterized by the triad of tubular basement disintegration, tubular atrophy with cyst development, and interstitial fibrosis. Some of glomerular sclerosis occurred. Cyst development at the corticomedullary border of the kidneys was the specific feature of NPH-MCKD. Conclusions Young patients with impaired tubular function should be suspected of NPH-MCKD. Renal ultrasound or computed tomography can provide an important clue. Multiple renal cysts at the corticomedullary border identified by renal biopsy can be a diagnostic indication for NPH-MCKD.