Renal Biopsy Research Articles

Monoclonal Membranous Glomerulopathy in a Patient with Positive Serology for Lupus Nephritis

Abstract Introduction/Objective Monoclonal membranous glomerulopathy (M-MGN) is a rare entity; only two reports are available in the literature. Monoclonal membranous glomerulopathy has been called either monoclonal immunoglobulin deposition disease associated with membranous features in a 3-patient small series report or membranous glomerulopathy with light chain restriction in another larger series with 28 cases. We report M-MGN in a patient with positive serology lupus. Methods/Case Report The patient was a 74-year-old man with hypertension and nephrotic range proteinuria (protein/creatinine ratio at 8.5). His serum creatinine remained normal at 0.6 mg/dL. The patient was positive for double-stranded DNA and ANA at low titer, but had reduced complement C3 and C4. Immunofixation was negative for monoclonal protein. The light microscopy of the renal biopsy revealed thickened loops of glomeruli with mild interstitial nephritis. Immunofluorescent studies showed a positive linear/granular pattern of IgG and lambda but negative kappa staining along the glomerular loops. Electron microscopy revealed smooth contoured stage 2 subepithelial deposits. An outside consultation confirmed our diagnosis and found IgG2 restriction in glomeruli. Electrophoresis revealed no monoclonal protein in the serum. Results (if a Case Study enter NA) NA Conclusion Our patient demonstrated M-MGN with mild interstitial nephritis; the latter may be related to his lupus status. As 30% of patients with M-MGN have either monoclonal serology or B-cell lymphoproliferative disorders, with most having a restricted IgG subtyping, a close follow-up and even chemotherapy for a B-cell clone should be considered.

Is Podocytopathy Associated with Gross Hematuria after COVID-19 Vaccination in Patients with Immunoglobulin A Nephropathy?

We experienced three cases of a fever and subsequent severe, prolonged gross hematuria after COVID-19 vaccination. A kidney biopsy revealed immunoglobulin A (IgA) nephropathy, and electron microscopy showed two types of podocytopathy (podocyte damage): loss of foot processes from the glomerular basement membrane and foot process effacement. Mesangial interposition was also present in cases 1 and 3 but not in case 2. Podocytopathy is known to be a cause of proteinuria; however, the reactions to COVID-19 vaccination described here suggest that it may also be related to hematuria in IgA nephropathy.

Evaluation of urinary volatile organic compounds as a novel metabolomic biomarker to assess chronic kidney disease progression

BackgroundThere is a need to develop accurate and reliable non-invasive methods to evaluate chronic kidney disease (CKD) status and assess disease progression. Given it is recognized that dysregulation in metabolic pathways occur from early CKD, there is a basis in utilizing metabolomic biomarkers to monitor CKD progression. Volatile Organic Compounds (VOCs), a form of metabolomic biomarker, are gaseous products of metabolic processes in organisms which are typically released with greater abundance in disease conditions when there is dysregulation in metabolism. How urinary VOCs reflect the abnormal metabolic profile of patients with CKD status is unknown. Our study aimed to explore this.MethodsIndividuals aged 18–75 years undergoing kidney biopsy were included. Pre-biopsy urine samples were collected. All biopsy samples had an interstitial fibrosis and tubular atrophy (IFTA) grade scored by standardized assessment. Urine supernatant was extracted from residue and sampled for stir bar sorptive extraction followed by Gas chromatography–mass spectrometry (GC-MS) analysis. Post-processing of GC-MS data separated complex mixtures of VOCs based on their volatility and polarity. Mass-to-charge ratios and fragment patterns were measured for individual VOCs identification and quantification. Linear discriminant analysis (LDA) was performed to assess the ability of urinary VOCs in discriminating between IFTA 0 (‘no or minimal IFTA’ i.e. <10%, IFTA), IFTA 1 (‘mild IFTA’ i.e. 10–25% IFTA) and IFTA ≥ 2 (‘moderate or severe IFTA’ i.e. >25% IFTA). Linear regression analysis adjusting for age, sex, estimated glomerular filtration rate, diabetes mellitus (DM) status, and albuminuria was conducted to determine significantly regulated urinary VOCs amongst the groups.Results64 study participants (22 individuals IFTA 0, 15 individuals IFTA 1, 27 individuals IFTA ≥ 2) were included. There were 34 VOCs identified from GC-MS which were statistically associated with correct classification between the IFTA groups, and LDA demonstrated individuals with IFTA 0, IFTA 1 and IFTA ≥ 2 could be significantly separated by their urinary VOCs profile (p < 0.001). Multivariate linear regression analysis reported 4 VOCs significantly upregulated in the IFTA 1 compared to the IFTA 0 group, and 2 VOCs significantly upregulated in the IFTA ≥ 2 compared to the IFTA 1 group (p < 0.05). Significantly upregulated urinary VOCs belonged to one of four functional groups - aldehydes, ketones, hydrocarbons, or alcohols.ConclusionsWe report novel links between urinary VOCs and tubulointerstitial histopathology. Our findings suggest the application of urinary VOCs as a metabolomic biomarker may have a useful clinical role to non-invasively assess CKD status during disease progression.

ClC-Kb pore mutation disrupts glycosylation and triggers distal tubular remodeling.

Mutations in the CLCNKB gene (1p36), encoding a basolateral chloride channel, ClC-Kb, cause type 3 Bartter's syndrome. We identified a family with a mixed Bartter's / Gitelman's phenotype and early-onset kidney failure and employing a candidate gene approach, discovered a homozygous mutation (CLCNKB c.499G>T [p.Gly167Cys]) in exon 6 of CLCNKB in the index patient. We then validated these results with Sanger and whole exome sequencing. Compared to wild-type ClC-Kb, the Gly167Cys mutant conducted less current and impaired, complex N-linked glycosylation in vitro. We demonstrated that loss of Gly-167, rather than gain of a mutant Cys, impairs complex glycosylation but that surface expression remains intact. Moreover, Asn364 was necessary for channel function and complex glycosylation. Morphologic evaluation of human kidney biopsies revealed typical basolateral localization of mutant Gly167Cys ClC-Kb in cortical distal tubular epithelia. However, we detected attenuated expression of distal sodium transport proteins, changes in abundance of distal tubule segments, and hypokalemia-associated intracellular condensates from the index patient compared to control nephrectomy specimens. The present data establish what we believe, are novel regulatory mechanisms of ClC-Kb activity and demonstrate nephron remodeling in man, caused by mutant ClC-Kb, with implications for renal electrolyte handling, blood pressure control, and kidney disease.

Development of a droplet digital PCR assay for the detection of BK polyomavirus.

The objective of this study was to establish a more sensitive and specific diagnostic method for detecting plasma BK polyomavirus (BKPyV) DNA load in patients after renal transplantation using droplet digital polymerase chain reaction (ddPCR) and to validate the methodology. The linear range, lower limit of detection, accuracy, precision, and specificity of the detection system were evaluated by using the WHO BKPyV standard (7.2 log10 IU/mL) as a reference, in accordance with the relevant documents of the Clinical and Laboratory Standards Institute. Plasma samples were collected from 74 renal transplantation patients with urinary BKPyV-DNA levels exceeding 7 log10 copies/mL. Quantitative PCR (qPCR) and ddPCR were performed, and their diagnostic efficacy for BKPyV-DNA in the diagnosis of BK polyomavirus-associated nephropathy was evaluated using a receiver operating characteristic (ROC) curve. The coefficients of variation for the repeated detection of BKPyV standard DNA were 2.55 and 4.71 at concentrations of 6.2 and 3.2 log10 IU/mL, respectively. The linear range was 2.2-6.2 log10 IU/mL, and the lowest detection limit was 100 IU/mL. By utilizing histopathological examination of renal biopsy as the gold standard for BKPyV diagnosis, the area under the ROC curve of 74 post-transplantation plasma samples detected by the ddPCR system was found to be 0.875 (95% CI: 0.797-0.953, P < 0.01). The optimal threshold was 512.86 copies/mL, with a sensitivity of 90.0% and a specificity of 67.6%. In comparison, the area under the ROC curve for qPCR was 0.668 (95% CI: 0.583-0.752, P < 0.01), with an optimal threshold of 11,481.54 copies/mL, a sensitivity of 35.0%, and a specificity of 100.0%. Pairwise comparison (Delong test) of the ROC curves of the two systems showed a significant difference in the area under the curve, with a difference of 0.207 and a P-value <0.01. The BKPyV nucleic acid detection system, based on ddPCR, is appropriate for the regular monitoring of the BK polyomavirus, specifically in plasma samples containing low viral DNA loads while it provides the benefits of both absolute quantification and high sensitivity.IMPORTANCEIt was previously believed that droplet digital polymerase chain reaction had limitations, including high cost, limited throughput, and cumbersome operation, which hindered its widespread application in clinical practice. However, the current fully automated digital PCR platform, combined with streamlined operations, can detect 96 samples at once, and the entire process can be completed within an hour, laying a solid foundation for its extensive use.

Genetic testing, a challenge to kidney biopsy? A case report

The field of genetic testing has experienced significant growth in medical practice since 1956, when the first genetic analysis was introduced. Persistent proteinuria has long been considered a strong risk factor for the progression of chronic renal failure, though, paradoxically, it can also be a benign process, as seen in individuals with mutations in the cubilin (CUBN) protein, specifically the C-terminal. CUBN is a peripheral protein that plays a crucial role in the receptor-mediated endocytotic reabsorption of albumin in the proximal tubule. In the past, there have been misinterpretations of CUBN variants with isolated proteinuria as glomerular injury, leading to unnecessary kidney biopsies and ineffective treatments. This paper discusses two siblings with a homozygous variant of (p.Tyr3018Ser) in the C-terminal of the CUBN protein, inherited from both heterozygous carrier parents. This case presents an opportunity to question our typical approach to proteinuria in an effort to avoid unnecessary kidney biopsies and the subsequent side effects of treatments, particularly for those with proteinuria.

A case of de novo glomerulonephritis following COVID-19 in a patient with preexistent IgA vasculitis.

During the unprecedented COVID-19 outbreak, new-onset or relapsing glomerulonephritis, such as ANCA-associated glomerulonephritis and Immunoglobulin A (IgA) nephropathy, following COVID-19 has been reported. However, to date, the association of COVID-19 with preexistent IgA vasculitis (IgAV) remains unclear. Here, we present the case of a 20-something old Japanese woman with preexistent IgAV who newly developed glomerulonephritis following COVID-19. At the diagnosis of IgAV, she had cutaneous purpura, joint pains, and gastrointestinal symptoms, but no signs of kidney involvement. Three months ago, she was tested positive for COVID-19 and subsequently developed hematuria and proteinuria. She was then admitted to our hospital and renal biopsy showed glomerular mesangial expansion and hypercellularity and cellular and fibrocellular crescents, accompanied by diffuse IgA and C3 deposits. With the diagnosis of de novo IgAV nephritis, the patient was treated with intravenous methylprednisolone followed by oral prednisolone. She had favorable responses to this treatment and has achieved and maintained the remission of hematuria and proteinuria after initiation of glucocorticoid therapy. Our case highlights that immune response to SARS-CoV-2 infection could trigger the onset of glomerulonephritis in the IgAV patients who have no renal involvement.

Case of successful treatment with glucocorticoid for isolated anti-centromere antibody-positive acute interstitial nephritis.

Acute interstitial nephritis (AIN) is known to cause acute kidney injury and is characterized by immunocyte infiltration and interstitial fibrosis. Primary etiologies include drugs, infections, and autoimmune disorders. Herein, we presented the case of a 78-year-old woman patient with AIN with anti-centromere antibody (ACA) positivity, secondary to an idiopathic immune system disorder. Her serum creatinine (sCr) was 0.67mg/dL 2months prior to consulting us, which increased to 2.79mg/dL. The renal biopsy revealed an AIN comprising interstitial infiltration with immunocytes and CD138 + cells. Furthermore, all other antibodies tested negative using immunofluorescence on both glomeruli and tubulointerstitial lesions. The ACA was elevated to a level of ≥ 500 U/mL. The ACA positive has been known to be accompanied by worsening kidney function in patients with systemic sclerosis and primary biliary cholangitis. However, any autoimmune disease were not diagnosed. Successful treatment with an initial dose of 30mg/day of glucocorticoids tapered to 25mg/day resulted in a decrease in the sCr to 1.53mg/dL 4weeks later. Nine months later, glucocorticoids was tapered, based on the threshold of a sCr of 1.03mg/dL and the titer of ACA of 291 U/mL. In this case, glucocorticoid treatment remarkably improved renal function in AIN containing CD138 + cells accompanied by a reduction of ACA titer. The etiology of ACA-positive AIN was unknown; however, the incidence of ACA-positive AIN should always be deliberated.

Urine Extracellular Vesicles Size Subsets as Lupus Nephritis Biomarkers.

Systemic lupus erythematosus (SLE) is an autoimmune disorder that often leads to kidney injury, known as lupus nephritis (LN). Although renal biopsy is the primary way to diagnose LN, it is invasive and not practical for regular monitoring. As an alternative, several groups have proposed urinary extracellular vesicles (uEVs) as potential biomarkers for LN, as recent studies have shown their significance in reflecting kidney-related diseases. As a result, we developed a flow cytometry approach that allowed us to determine that LN patients exhibited a significantly higher total uEV concentration compared to SLE patients without kidney involvement. Additionally, an analysis of different-sized uEV subsets revealed that microvesicles ranging from 0.3 to 0.5 μm showed the most promise for distinguishing LN. These findings indicate that evaluating uEV concentration and size distribution could be a valuable diagnostic and monitoring tool for LN, pending further validation in more comprehensive studies.

Vasculitis associated with VEXAS syndrome.

To define the prevalence, distribution, and characteristics of patients with VEXAS who have confirmed vasculitis. Patients with VEXAS syndrome, verified by positive UBA1 mutation, were included. Chart review was performed to identify. characteristics and outcomes. Vasculitis diagnosis was based on either histopathology showing vascular inflammation or non-invasive angiography findings. Summary statistics were calculated. Eighty-nine patients met inclusion criteria. All were male with a median age of onset of 66.9 years (IQR 60.1, 72.7). Median (IQR) follow up was 3.8(2.2-5.5) years during which 21 patients (23.6%) had evidence of vasculitis. Vasculitis subtypes included small vessel vasculitis (19.1%), cutaneous medium vessel vasculitis (2.2%), and large vessel vasculitis (2.2%). No patient had more than one vessel size involved. Histopathology in small vessel vasculitis patients was consistent with cutaneous leukocytoclastic vasculitis in the majority, though one patient had leukocytoclastic peritubular capillaritis on renal biopsy. Cranial symptoms (headache, vision changes, or jaw pain) were noted in 18.0%. Two additional patients not experiencing cranial symptoms exhibited large vessel involvement with confirmed carotid thickening on non-invasive angiography; one of these had a positive temporal artery biopsy. VEXAS syndrome manifests as a variable vessel vasculitis in a quarter of patients, with cutaneous small and medium vessel involvement being particularly common. Some patients may have positive ANCA serologies or even renal vasculitis leading to misdiagnosis. Cranial symptoms are common and may mimic giant cell arteritis, though documented large vessel inflammation is rare.

ANCA-Negative Pauci-Immune Glomerulonephritis: A review

Background: Pauci-immune glomerulonephritis (PIGN) is typically secondary to antineutrophil cytoplasmic antibodies (ANCA) small-vessel vasculitis. However, some cases lack detectable circulating ANCA and are called ANCA-negative PIGN (seronegative PIGN). The reported incidence of this varies greatly. Its relationship to ANCA-associated vasculitis (AAV) is unclear. Summary: This review explores the pathophysiology of seronegative PIGN and summarizes findings from twelve studies focusing on this disease. The role of neutrophils appears to be central, with activation through cellular and humoral mechanisms. Most studies have noted less extrarenal involvement and more chronic changes in the kidney biopsy in seronegative PIGN compared to ANCA-positive cases. Studies have mostly reported using corticosteroids with cyclophosphamide for induction therapy and azathioprine for maintenance. The renal survival was noted to be lower compared to ANCA-positive PIGN. Key messages: Whether ANCA-negative PIGN represents a distinct disease or is part of the AAV spectrum remains unclear. Prospective large-scale studies are needed to understand this disease for optimal diagnosis and management.

Safety and Efficacy of Avacopan in Patients with C3 Glomerulopathy: Randomized, Double-Blind Clinical Trial.

Complement 3 (C3) glomerulopathy is a rare autoimmune disorder characterized by activation of the alternative complement pathway with isolated or dominant C3 deposition in glomeruli. Patients with C3 glomerulopathy may develop progressive deterioration in kidney function and kidney failure. We studied the safety and efficacy of avacopan 30 mg twice daily in patients with C3 glomerulopathy (N=57) with elevated (> 244 ng/mL) and normal (≤ 244 ng/mL) levels of C5b-9 in a randomized, double-blind, placebo-controlled, phase 2 trial, with kidney biopsies performed pre-randomization and at 26 and 52 weeks. The primary outcome was the percent change from baseline to week 26 in C3 glomerulopathy histologic index for disease activity. The study was conducted in patients with C3 glomerulopathy, including C3 glomerulonephritis and DDD. The median study duration was 60.0 weeks (interquartile range 59.9 to 61.0). There were no significant differences in the primary outcome between the avacopan and the placebo group; least square mean treatment difference (95% CI) = -0.0 (-1.9 to 1.8). The secondary measures of efficacy including C3 Glomerulopathy Histological Index for disease chronicity, urine protein:creatinine ratio (UPCR), and estimated glomerular filtration rate (eGFR) were not different between treatment groups. The overall incidence and type of adverse events for both treatment groups were comparable. No deaths were reported during the study, and no new safety signals were detected. The primary end point for the study was not met; other clinical effects of avacopan to improve certain key kidney function parameters and slow disease progression were variable and require further evaluation.

Clinical and genetic analysis of a child with co-morbid progressive IgA nephropathy and COQ8B-associated glomerulopathy

To explore the genetic etiology and clinical outcome of a child with co-morbid progressive IgA nephropathy and COQ8B-associated glomerulopathy. A child who was admitted to Peking University First Hospital on March 2, 2021 was selected as the study subject. Genomic DNA was extracted from peripheral blood samples from the child and his parents and sister. Whole exome sequencing was carried out, and candidate variant was verified by Sanger sequencing. This study was approved by the Peking University First Hospital (Ethics No. 2016[1029]). The child, a 7-year-old boy who had developed proteinuria 8 months before, was diagnosed with IgA nephropathy (M1E1S1T1C1). With steroid, cyclophosphamide, cyclosporine and angiotensin-converting enzyme inhibitor therapy, partial remission of proteinuria was achieved. However, his serum creatinine level had increased from 53.8 mol/L at the onset of disease to 86.7 mol/L after 3.9 years, along with massive proteinuria. Kidney biopsy still indicated IgA nephropathy (M0E0S1T0C0). The child was found to harbor a homozygous c.737G>A (p.Ser246Asn) missense variant of the COQ8B gene, for which his parents and sister were heterozygous carriers. The variant was predicted to be pathogenic (PS1+PM2_Supporting+PM3+PP3+PP4) based on the guidelines from the American College of Medical Genetics and Genomics. The child was treated with high-dose coenzyme Q10 in combination with steroid and/or mycophenolate mofetil, though his serum creatinine level still increased to 286 mol/L after 7.3 years, which conformed to a chronic kidney disorder with glomerular filtration rate category of G3b. The homozygous c.737G>A missense variants of the COQ8B gene probably underlay the progressive kidney dysfunction in this child. For children with IgA nephropathy presenting with atypical clinical manifestations, unsatisfactory therapeutic effect, and/or early onset of kidney function decline, coexistence of other diseases should be suspected.

Late-onset renal TMA and tubular injury in cobalamin C disease: a report of three cases and literature review

BackgroundMutation of MMACHC gene causes cobalamin C disease (cblC), an inherited metabolic disorder, which presents as combined methylmalonic aciduria (MMA-uria) and hyperhomocysteinaemia in clinical. Renal complications may also be present in patients with this inborn deficiency. The most common histological change is thrombotic microangiopathy (TMA). However, to our acknowledge, renal tubular injury in the late-onset presentation of cblC is rarely been reported. This study provides a detailed description of the characteristics of kidney disease in cblC deficiency, aiming to improve the early recognition of this treatable disease for clinical nephrologists.Case presentationHere we described three teenage patients who presented with hematuria, proteinuria, and hypertension in clinical presentation. They were diagnosed with renal involvement due to cblC deficiency after laboratory tests revealing elevated serum and urine homocysteine, renal biopsy showing TMA and tubular injury, along with genetic testing showing heterogeneous compound mutations in MMACHC. Hydroxocobalamin, betaine, and L-carnitine were administered to these patients. All of them got improved, with decreased homocysteine, controlled blood pressure, and kidney outcomes recovered.ConclusionsThe clinical diagnosis of cblC disease associated with kidney injury should be considered in patients with unclear TMA accompanied by a high concentration of serum homocysteine, even in teenagers or adults. Early diagnosis and timely intervention are vital to improving the prognosis of cobalamin C disease.Clinical Trial NumberNot applicable.

Clinical relevance of proteinuria selectivity index and fractional excretion of sodium in patients with nephrotic syndrome

Proteinuria selectivity index (PSI) is a potential tool for histological classification and prediction of treatment response in nephrotic syndrome, but evidence is insufficient. Clinical relevance of fractional excretion of sodium (FENa) in nephrotic syndrome remains largely unexplored. This multicenter retrospective study included patients with nephrotic syndrome who underwent kidney biopsy between January 2012 and June 2022. Optimal cutoffs for predicting complete remission based on PSI and FENa were determined using receiver operating characteristic curves. Patients were divided into two groups using these cutoffs and followed until complete remission. Of the 611 patients included, 177 had minimal change disease (MCD), 52 had focal segmental glomerulosclerosis (FSGS), and 149 had membranous nephropathy (MN). Median (interquartile range) PSI were 0.14 (0.09–0.19) for MCD, 0.33 (0.23–0.40) for FSGS, and 0.20 (0.14–0.30) for MN. FENa were 0.24 (0.09–0.68), 1.03 (0.50–2.14), and 0.78 (0.41–1.28). Patients with low PSI and FENa had a higher incidence of complete remission. Cox regression analyses demonstrated that both parameters were associated with achieving complete remission (HR 2.73 [95% CI 1.97–3.81] and HR 1.93 [95% CI 1.46–2.55], respectively). PSI and FENa may be useful for histological classification and predicting remission in nephrotic syndrome.

Self-Supervised Learning for Feature Extraction from Glomerular Images and Disease Classification with Minimal Annotations.

Deep learning has great potential in digital kidney pathology. However, its effectiveness depends heavily on the availability of extensively labeled datasets, which are often limited due to the specialized knowledge and time required for their creation. This limitation hinders the widespread application of deep learning for the analysis of kidney biopsy images. We applied self-distillation with no labels (DINO), a self-supervised learning method, to a dataset of 10,423 glomerular images obtained from 384 PAS-stained kidney biopsy slides. Glomerular features extracted from the DINO-pretrained backbone were visualized using principal component analysis (PCA). We then performed classification tasks by adding either k-nearest neighbor (kNN) classifiers or linear head layers to the DINO-pretrained or ImageNet-pretrained backbones. These models were trained on our labeled classification dataset. Performance was evaluated using metrics such as the area under the receiver operating characteristic curve (ROC-AUC). The classification tasks encompassed four disease categories (minimal change disease, mesangial proliferative glomerulonephritis, membranous nephropathy, and diabetic nephropathy) as well as clinical parameters such as hypertension, proteinuria, and hematuria. PCA visualization revealed distinct principal components corresponding to different glomerular structures, demonstrating the capability of the DINO-pretrained backbone to capture morphological features. In disease classification, the DINO-pretrained transferred model (ROC-AUC = 0.93) outperformed the ImageNet-pretrained fine-tuned model (ROC-AUC = 0.89). When the labeled data were limited, the ImageNet-pretrained fine-tuned model's ROC-AUC dropped to 0.76 (95% confidence interval [CI], 0.72-0.80), whereas the DINO-pretrained transferred model maintained superior performance (ROC-AUC 0.88, 95% CI 0.86-0.90). The DINO-pretrained transferred model also exhibited higher AUCs for the classification of several clinical parameters. External validation using two independent datasets confirmed DINO pre-training's superiority, particularly when labeled data were limited. The application of DINO to unlabeled PAS-stained glomerular images facilitated the extraction of histological features that can be effectively utilized for disease classification.

Clinical correlates and pathology of non-diabetic renal disease in diabetes mellitus

Objectives: Early identification and differentiation of patients with non-diabetic renal disease (NDRD) from diabetic nephropathy (DN) or those with NDRD superimposed on DN improves the prognosis and reduces associated morbidity. The objectives of the study were to compare the clinical profile, nature of renal involvement, and etiopathogenesis (renal biopsy) of patients with isolated NDRD and NDRD superimposed on DN. Materials and Methods: It is a descriptive study in patients with T2D and renal involvement suggestive of non-diabetic etiology further evaluated with renal biopsy and grouped as NDRD alone or NDRD with DN. Results: Of the total 50, 66% were male, the mean age was 55.57 ± 12.28 years, and all were proteinuric. Overall, isolated NDRD and NDRD superimposed on DN were observed in 64% and 36% of patients, respectively. Diabetic retinopathy was absent in 82% of cases. The most common finding in isolated NDRD was membranous nephropathy, followed by immunoglobulin A (IgA) nephropathy and rapid progression of glomerular nephritis (RPGN). At the same time, in the NDRD and DN group, maximum patients displayed IgA nephropathy followed by acute tubular necrosis and RPGN. The incidence of atypical features of renal disease was almost twice as high in the isolated NDRD group than in the group with both NDRD + DN. Conclusion: NDRDs are highly prevalent, and DN may superimpose these. Recognizing NDRD solely on the basis of clinical indicators is challenging. Therefore, histopathological analysis seems essential to accurately diagnose NDRD in diabetic patients to reduce the probability of missed NDRD diagnosis and initiate prompt treatment.

Machine learning-based diagnostic prediction of minimal change disease: model development study

Minimal change disease (MCD) is a common cause of nephrotic syndrome. Due to its rapid progression, early detection is essential; however, definitive diagnosis requires invasive kidney biopsy. This study aims to develop non-invasive predictive models for diagnosing MCD by machine learning. We retrospectively collected data on demographic characteristics, blood tests, and urine tests from patients with nephrotic syndrome who underwent kidney biopsy. We applied four machine learning algorithms—TabPFN, LightGBM, Random Forest, and Artificial Neural Network—and logistic regression. We compared their performance using stratified 5-repeated 5-fold cross-validation for the area under the receiver operating characteristic curve (AUROC) and the area under the precision-recall curve (AUPRC). Variable importance was evaluated using the SHapley Additive exPlanations (SHAP) method. A total of 248 patients were included, with 82 cases (33%) were diagnosed with MCD. TabPFN demonstrated the best performance with an AUROC of 0.915 (95% CI 0.896–0.932) and an AUPRC of 0.840 (95% CI 0.807–0.872). The SHAP methods identified C3, total cholesterol, and urine red blood cells as key predictors for TabPFN, consistent with previous reports. Machine learning models could be valuable non-invasive diagnostic tools for MCD.

Is It a Tumor or Not? A Case of Focal Segmental Glomerulosclerosis Secondary to Type 2 Diabetes with a Concomitant Renal Pseudotumor

Background: Focal segmental glomerulosclerosis (FSGS) is a histologic pattern of glomerular injury that can be primary or secondary to various conditions, including obesity, diabetes, and hypertension. Renal masses, often detected incidentally, can be benign or malignant, with renal cell carcinoma (RCC) being the most common. This case report presents a patient with FSGS secondary to type 2 diabetes and a concomitant renal pseudotumor, initially suspected to be RCC. Case presentation: A 60-year-old woman presented with weakness, fever, and weight loss. Imaging revealed a renal mass, initially suspected to be RCC. A kidney biopsy revealed FSGS, and further evaluation confirmed type 2 diabetes. After controlling her diabetes and hypertension, the renal mass regressed, suggesting a pseudotumor. Conclusion: This case highlights the importance of considering pseudotumors in the differential diagnosis of renal masses, especially in patients with comorbidities such as diabetes. A kidney biopsy can help avoid unnecessary invasive procedures like nephrectomy.

Dynamics of CD4+ and CD8+ Lymphocytic Inflammatory Infiltrates in Lupus Nephritis.

Lupus nephritis (LN) is a common clinical manifestation of systemic lupus erythematosus (SLE). Our study aims to quantitatively analyze CD4+ and CD8+ lymphocytes in different areas and LN classes and describe a specific distribution pattern that is correlated with the severity of LN-specific lesions. In total, 53 LN renal biopsies were immunohistochemically investigated using anti-CD4 and anti-CD8 antibodies. T lymphocytes were counted in 3 areas, including intraglomerular, periglomerular, and interstitial regions. The severity of glomerular and tubulo-interstitial lesions was assessed using an original semi-quantitative algorithm based on the renal corpuscle score (RC_S) and the tubulo-interstitial score (TI_S). The number of CD8+ T lymphocytes was higher than that of CD4+ T lymphocytes in each of the three areas and in each LN class, showing statistically significant differences. ANOVA analysis of all LN classes showed significant differences between periglomerular and interstitial CD4+ and CD8+ T lymphocytes, respectively. Irrespective of location, the number of CD8+ T lymphocytes statistically correlates with the RC_S and the TI_S; no significant correlations were found between the number of CD4+ T lymphocytes and the RC_S and the TI_S for all three considered areas. Our data provide strong evidence supporting the major role of CD8+ lymphocytes in LN lesion progression, with CD4+ lymphocytes playing a limited role.