Percutaneous kidney biopsies in children: a 24-year review in a tertiary center in northern Portugal.

INTRODUCTION: Percutaneous kidney biopsy (KB) is crucial to the diagnosis and management of several renal pathologies. National data on native KB in pediatric patients are scarce. We aimed to review the demographic and clinical characteristics and histopathological patterns in children who underwent native percutaneous KB over 24 years. METHODS: Retrospective observational study of patients undergoing native percutaneous KB in a pediatric nephrology unit between 1998 and 2021, comparing 3 periods: period 1 (1998-2005), period 2 (2006-2013), and period 3 (2014-2021). RESULTS: We found that 228 KB were performed, 78 (34.2%) in period 1, 91 (39.9%) in period 2, and 59 (25.9%) in period 3. The median age at KB was 11 (7-14) years. The main indications for KB were nephrotic syndrome (NS) (42.9%), hematuria and/or non-nephrotic proteinuria (35.5%), and acute kidney injury (13.2%). Primary glomerulopathies were more frequent (67.1%), particularly minimal change disease (MCD) (25.4%), IgA nephropathy (12.7%), and mesangioproliferative glomerulonephritis (GN) (8.8%). Of the secondary glomerulopathies, lupus nephritis (LN) was the most prevalent (11.8%). In group 1, hematuria and/or non-nephrotic proteinuria were the main reasons for KB, as opposed to NS in groups 2 and 3 (p < 0.01). LN showed an increasing trend (period 1-3: 2.6%-5.3%) and focal segmental glomerular sclerosis (FSGS) showed a slight decreasing trend (period 1-3: 3.1%-1.8%), without statistical significance. CONCLUSIONS: The main indication for KB was NS, which increased over time, justifying the finding of MCD as main histological diagnosis. LN showed an increase in incidence over time, while FSGS cases did not increase.

Clinical and pathological findings of IgA nephropathy following SARS-CoV-2 infection.

The features of IgA nephropathy (IgAN) after SARS-CoV-2 infection have not been well characterized. In this study, we compared the clinical and pathological characteristics of patients with IgAN who had experienced SARS-CoV-2 infection to those who had not. We conducted a retrospective study that enrolled 38 patients with biopsy-proven IgAN following SARS-CoV-2 infection with 4 months (post-SARS-CoV-2 infection group) and 1154 patients with IgAN prior to the pandemic (pre-SARS-CoV-2 infection group). Among the SARS-CoV-2 group cases, 61% were females. The average duration from SARS-CoV-2 infection to renal biopsy was 78.6 days. Prior to SARS-CoV-2 infection, the patients had different presentations of nephropathy. One patient had isolated hematuria, two had isolated proteinuria, twenty presented with both hematuria and proteinuria, and one patient had elevated serum creatinine. Additionally, there were eight cases with uncertain nephropathy history, and six cases did not have a history of nephropathy. Following SARS-CoV-2 infection, five patients experienced gross hematuria, one case exhibited creatinine elevation, and five cases showed an increase in proteinuria. The group of patients infected with SARS-CoV-2 after the COVID-19 pandemic exhibited older age, higher hypertension ratio and lower eGFR values compared to the pre-SARS-CoV-2 infection group. As for pathological parameters, a higher proportion of patients in the post-SARS-CoV-2 infection group exhibited a higher percentage of sclerotic glomeruli and glomerular ischemic sclerosis. There were no significant differences observed between the two groups in terms of therapy involving steroids, immunosuppressants, or RAS inhibitors. IgA nephropathy patients who were infected with SARS-CoV-2 were generally older and experienced more severe kidney damage compared to those without SARS-CoV-2 infection.

Gross Hematuria Does not Affect the Selection of Nephrectomy Types for Clinical Stage 1 Clear Cell Renal Cell Carcinoma: A Multicenter, Retrospective Cohort Study.

PURPOSE: This study aimed to discuss the correlation between gross hematuria and postoperative upstaging (from T1 to T3a) in patients with cT1 clear cell renal cell carcinoma (ccRCC) and to compare oncologic outcomes of partial nephrectomy (PN) and radical nephrectomy (RN) in patients with gross hematuria. METHODS: A total of 2145 patients who met the criteria were enrolled in the study (including 363 patients with gross hematuria). The least absolute selection and shrinkage operator logistic regression was used to evaluate the risk factor of postoperative pathological upstaging. The propensity score matching (PSM) and stable inverse probability of treatment weighting (IPTW) analysis were used to balance the confounding factors. The Kaplan-Meier analysis and multivariate Cox proportional risk regression model were used to assess the prognosis. RESULTS: Gross hematuria was a risk factor of postoperative pathological upstaging (odds ratio [OR] = 3.96; 95% confidence interval [CI] 2.44-6.42; P < 0.001). After PSM and stable IPTW adjustment, the characteristics were similar in corresponding patients in the PN and RN groups. In the PSM cohort, PN did not have a statistically significant impact on recurrence-free survival (hazard ratio [HR] = 1.48; 95% CI 0.25-8.88; P = 0.67), metastasis-free survival (HR = 1.24; 95% CI 0.33-4.66; P = 0.75), and overall survival (HR = 1.46; 95% CI 0.31-6.73; P = 0.63) compared with RN. The results were confirmed in sensitivity analyses. CONCLUSIONS: Although gross hematuria was associated with postoperative pathological upstaging in patients with cT1 ccRCC, PN should still be the preferred treatment for such patients.

Nephrotic proteinuria and hematuria with newly diagnosed IgA nephropathy after liver transplant: A case report.

BACKGROUND: IgA nephropathy is a renal lesion in patients with end-stage liver disease, called hepatic IgA nephropathy. The common manifestation of hepatic IgA nephropathy is microscopic hematuria. Sirolimus, often used to prevent organ rejection, has been reported to induce proteinuria after organ transplantation. But few cases of nephrotic proteinuria and hematuria are reported. CASE PRESENTATION: In this case, a 45-year-old male with a long history of hepatic B virus infection and liver cirrhosis, received liver transplant and was taking sirolimus as one of his immunosuppression drugs. Overt proteinuria and hematuria occurred. With no proteinuria history before, renal biopsy was performed, which indicated IgA nephropathy. CONCLUSION: We reported a liver recipient, who was taking sirolimus, developing nephrotic proteinuria and hematuria with IgA nephropathy. Further studies need to be carried out to disclose mechanism behind this phenomenon.

Hemangioma of the Urinary Bladder: A Brief Narrative Review of Their Diagnosis, Histology, and Treatment Options.

BACKGROUND: Hemangioma of the urinary bladder is a rare benign tumor. Although benign, their presenting symptoms are alarming for both patients and doctors, and their rarity makes them challenging to correctly diagnosis and treat. This review paper summarizes current knowledge about hemangioma of the urinary bladder, treatment options, and follow-up modalities. SUMMARY: After the kidney, the bladder is the second most common location of hemangiomas in the urinary tract. There is painless gross hematuria on clinical presentation once the lesion has eroded the urothelium. Magnetic resonance imaging (MRI) has been reported to be valuable in diagnosing soft-tissue hemangiomas. Cystoscopic findings of a sessile, blue, multilocular mass suggest hemangioma. Most tumors are solitary, smaller than 3 cm, and have smooth or irregular surfaces. Histologically, lesions comprise numerous proliferative capillaries with thin-walled, dilated, blood-filled vessels lined with flattened endothelium. The treatment of patients with hemangioma has been controversial. It depends on the tumor size and the degree of penetration. The prognosis of these tumors is excellent. KEY MESSAGES: Despite the widespread use of MRI, CT, and endoscopy in evaluating hematuria, hemangioma remains one of the rarest bladder tumors. Moreover, only a histological examination can confirm the diagnosis. Transurethral resection, fulguration, and YAG laser ablation are standard treatments for small tumors. In terms of follow-up, cystoscopy after 6 months of treatment helps assess recurrence. In addition, MRI is a practical, noninvasive technique for follow-up of small hemangiomas.

Current treatment status of IgA nephropathy in Japan: a questionnaire survey.

BACKGROUND: In 2020, the Committee of Clinical Practical Guideline for IgA Nephropathy (IgAN) revised the clinical practice guidelines. Herein, we conducted a questionnaire survey to assess the potential discrepancies between clinical practice guidelines and real-world practice in Japan. METHODS: A web-based survey of members of the Japanese Society of Nephrology was conducted between November 15 and December 28, 2021. RESULTS: A total of 217 members (internal physicians: 203, pediatricians: 14) responded to the questionnaire. Of these respondents, 94.0% answered that the clinical practice guidelines were referred to "always" or "often." Approximately 66.4% respondents answered that histological grade (H-Grade) derived from the "Clinical Guidelines for IgA nephropathy in Japan, 3rd version" and the "Oxford classification" were used for pathological classification. Moreover, 73.7% respondents answered that the risk grade (R-grade) derived from the "Clinical Guidelines for IgA nephropathy in Japan, 3rd version" was referred to for risk stratification. The prescription rate of renin-angiotensin system blockers increased based on urinary protein levels (> 1.0 g/day: 88.6%, 0.5-1.0 g/day: 71.0%, < 0.5 g/day: 25.0%). Similarly, the prescription rate of corticosteroids increased according to proteinuria levels (> 1.0 g/day: 77.8%, 0.5-1.0 g/day: 52.8%, < 0.5 g/day: 11.9%). The respondents emphasized on hematuria when using corticosteroids. In cases of hematuria, the indication rate for corticosteroids was higher than in those without hematuria, even if the urinary protein level was 1 g/gCr or less. Few severe infectious diseases or serious deterioration in glycemic control were reported during corticosteroid use. CONCLUSION: Our questionnaire survey revealed real-world aspects of IgAN treatment in Japan.

A Case of Urinary Bladder Malakoplakia in a Young French Bulldog: Diagnostic and Therapeutic Issues.

A 3-month-old female French Bulldog presented with hematuria, severe pollakiuria, and urinary incontinence lasting for 1.5 months. Broad-spectrum empirical antibiotic therapy and nonsteroidal anti-inflammatory drugs were initiated by the referring veterinarian. Due to a lack of improvement, the dog was referred. At referral examination, urinary clinical signs persisted (hematuria, severe pollakiuria) and a firm bladder was noted. Abdominal ultrasonography revealed severe, diffuse bladder wall thickening with a significant reduction in the bladder lumen. Urinary tract endoscopy showed whitish exophytic proliferations throughout the entire bladder wall. Histological bladder wall analysis led to a diagnosis of bladder malakoplakia. Prolonged antibiotic therapy with fluoroquinolones was prescribed and resulted in clinical remission despite persistent bacteria in the bladder wall. This report describes a case of successfully medically managed bladder malakoplakia, a very rare condition in veterinary medicine, well documented in humans.

Clinicopathological spectrum of biopsy-proven renal diseases of patients at a single center in Sri Lanka: a cross sectional retrospective review.

BACKGROUND: The clinical presentation of renal diseases can vary widely. The lack of a comprehensive national registry for Sri Lanka makes it difficult to provide a detailed record of the various clinical presentations and histopathology of renal disorders in the nation. Therefore, this study aims to provide a record of the spectrum of renal diseases in Sri Lanka. METHODS: Renal biopsies performed at the nephrology unit in Colombo South Teaching Hospital (CSTH), Sri Lanka from March 2018 to October 2019 was retrospectively studied. Indications for renal biopsy were nephrotic range proteinuria, sub nephrotic range proteinuria, acute kidney injury without obvious etiology, chronic renal disease without obvious etiology and haematuria. RESULTS: A total of 140 native kidney biopsies were analyzed in which majority were females (55.7%). The mean age of the population was 46 ± 15.3 years. The most common indications for renal biopsy were nephrotic range proteinuria (54.3%), followed by sub-nephrotic range proteinuria (14.3%), nephrotic range proteinuria with haematuria (14.3%), sub-nephrotic range proteinuria with haematuria (9.3%), AKI without known cause (4.3%), and CKD without known cause (3.6%). The leading histopathological diagnoses were FSGS (22.1%), lupus nephritis (20%), PSGN (17.1%), DN (12.1%), HTN (9.3%), MCD (6.4%), IgA nephropathy (5.7%), IN (4.3%), vasculitis (2.1%), and MGN (0.7%). CONCLUSIONS: The most common indication for renal biopsy was nephrotic range proteinuria in our population. FSGS was the most prevalent histopathological diagnosis and the least frequent diagnosis reported was MGN. The spectrum of renal diseases could differ according to the study location and it changes over time. Therefore, a renal biopsy registry is needed for documenting the changing disease pattern in Sri Lanka.

Coexistence of cryoglobulinemia and ANCA-associated vasculitis in a chronic brucellosis patient -a case report and literature review.

BACKGROUND: The renal involvement of brucellosis is not common. Here we reported a rare case of chronic brucellosis accompanied by nephritic syndrome, acute kidney injury, the coexistence of cryoglobulinemia and antineutrophil cytoplasmic autoantibodies (ANCA) associated vasculitis (AAV) superimposed on iliac aortic stent implantation. The diagnosis and treatment of the case are instructive. CASE PRESENTATION: A 49-year-old man with hypertension and iliac aortic stent implantation was admitted for unexplained renal failure with signs of nephritic syndrome, congestive heart failure, moderate anemia and livedoid change in the left sole with pain. His past history included chronic brucellosis and he just underwent the recurrence and completed the 6 weeks of antibiotics treatment. He demonstrated positive cytoplasmic/proteinase 3 ANCA, mixed type cryoglobulinemia and decreased C3. The kidney biopsy revealed endocapillary proliferative glomerulonephritis with a small amount of crescent formation. Immunofluorescence staining revealed only C3-positive staining. In accordance with clinical and laboratory findings, post-infective acute glomerulonephritis superimposed with AAV was diagnosed. The patient was treated with corticosteroids and antibiotics and sustained alleviation of renal function and brucellosis was achieved during the course of a 3-month follow-up. CONCLUSIONS: Here we describe the diagnostic and treatment challenge in a patient with chronic brucellosis related glomerulonephritis accompanied by the coexistence of AAV and cryoglobulinemia. Renal biopsy confirmed the diagnosis of postinfectious acute glomerulonephritis overlapping with ANCA related crescentic glomerulonephritis, which was not ever reported in the literature. The patient showed a good response to steroid treatment which indicated the immunity-induced kidney injury. Meanwhile, it is essential to recognize and actively treat the coexisting brucellosis even when there are no clinical signs of the active stage of infection. This is the critical point for a salutary patient outcome for brucellosis associated renal complications.

Genetic features and kidney morphological changes in women with X-linked Alport syndrome.

BACKGROUND: X-linked Alport syndrome (XLAS) caused by COL4A5 pathogenic variants usually has heterogeneous phenotypes in female patients. The genetic characteristics and glomerular basement membrane (GBM) morphological changes in women with XLAS need to been further investigated. METHODS: A total of 83 women and 187 men with causative COL4A5 variants were enrolled for comparative analysis. RESULTS: Women were more frequently carrying de novo COL4A5 variants compared with men (47% vs 8%, p=0.001). The clinical manifestations in women were variable, and no genotype-phenotype correlation was observed. Coinherited podocyte-related genes, including TRPC6, TBC1D8B, INF2 and MYH9, were identified in two women and five men, and the modifying effects of coinherited genes contributed to the heterogeneous phenotypes in these patients. X-chromosome inactivation (XCI) analysis of 16 women showed that 25% were skewed XCI. One patient preferentially expressing the mutant COL4A5 gene developed moderate proteinuria, and two patients preferentially expressing the wild-type COL4A5 gene presented with haematuria only. GBM ultrastructural evaluation demonstrated that the degree of GBM lesions was associated with the decline in kidney function for both genders, but more severe GBM changes were found in men compared with women. CONCLUSIONS: The high frequency of de novo variants carried by women indicates that the lack of family history tends to make them susceptible to be underdiagnosed. Coinherited podocyte-related genes are potential contributors to the heterogeneous phenotype of some women. Furthermore, the association between the degree of GBM lesions and decline in kidney function is valuable in evaluating the prognosis for patients with XLAS.

Association between COVID-19 vaccination and relapse of glomerulonephritis.

BACKGROUND: Vaccines for coronavirus disease 2019 (COVID-19) have been developed and are recommended for patients with chronic kidney disease; however, it has been reported that glomerulonephritis worsens after vaccination. We aimed to elucidate the incidence and association between COVID-19 vaccination and glomerulonephritis relapse. METHODS: We investigated the onset of renal events and adverse reactions after COVID-19 vaccination in 111 patients diagnosed with glomerulonephritis. Renal events were defined as worsening hematuria, increased proteinuria, and an increased creatine level over 1.5-fold from baseline. RESULTS: Patients were 57 ± 18 years old (55.9% female) and had an estimated glomerular filtration rate of 57.0 ± 25.0 ml/min/1.73 m2. A pathological diagnosis of IgA nephropathy was confirmed in 55.0%, minimal change disease in 22.5%, and membranous nephropathy in 10.8% of the patients. The BNT162b2 (Pfizer) and mRNA-1273 (Moderna) vaccines were administered in 88.2% and 11.7% of the cases, respectively. Renal events were observed in 22.5% of patients, 10.8% had increased proteinuria, 12.6% had worsening hematuria, and 1.8% received additional immunosuppressive treatment. Only 0.9% required temporary hemodialysis from exacerbation of renal dysfunction. Renal events were higher in younger patients (P = 0.02), being highest in those with IgA nephropathy, but there was no difference in the incidence between pathological diagnoses. There was a significantly higher incidence of renal events in patients with fever (P = 0.02). CONCLUSIONS: COVID-19 vaccination and glomerulonephritis relapse may be related, but further research is needed.

A case report of atypical anti-glomerular basement membrane disease.

BACKGROUND: Anti-glomerular basement membrane (anti-GBM) disease is characterized by crescentic necrotizing glomerulonephritis, with linear deposits of immunoglobulin G (IgG) in the GBM. Classic anti-GBM disease is clinically associated with rapidly progressive glomerulonephritis with or without pulmonary hemorrhage. Some patients have a better renal prognosis and milder symptoms than those with classic anti-GBM disease, which is termed atypical anti-GBM disease. CASE PRESENTATION: A 43-year-old Japanese woman was admitted to our hospital complaining of hematuria that had persisted for more than one month. Serological examination revealed negativity for anti-nuclear, anti-neutrophilic cytoplasmic, and anti-GBM antibodies. However, renal biopsy showed cellular crescents. Immunofluorescence revealed strong diffuse linear capillary loop staining for IgG. An indirect immunofluorescence antibody method was performed by applying the patient serum to normal kidney tissue to confirm the presence of autoantibodies binding to the GBM. Using this method, anti-GBM antibodies were detected. The patient was treated with high-dose steroids, cyclophosphamide, and plasma exchange. Aggressive treatment resolved proteinuria and hematuria and improved renal function. CONCLUSIONS: Renal biopsy is crucial in the diagnosis of anti-GBM disease, especially when serological tests are negative. Accurately identifying the presence of anti-GBM disease is important to initiate optimal treatment.

What is the prognosis of ANCA-associated glomerulonephritis with immune deposition?

OBJECTIVES: This study aimed to analyze histological and clinical characteristics of patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) showing renal involvement to investigate the associations between immune complexes (IC) and clinicopathological indicators, and explore the renal outcomes of AAV. METHODS: We retrospectively evaluated the histopathological features and clinical characteristics of 80 renal biopsies of patients with AAV with renal involvement. Renal morphology was classified into two (with and without the presence of IC and complement deposition). Endpoints included end-stage kidney disease (ESKD) and death. RESULTS: Compared with patients without IC, patients with immune deposition had lower complement C3 (0.80 ± 0.27 vs. 0.93 ± 0.20, p = 0.024), more severe hematuria [133 (46-299) vs. 33 (15-115), p = 0.001] but had milder chronic pathology, including chronic tubular atrophy (p = 0.03), chronic interstitial fibrosis (p = 0.049). Patients in the immune deposition group showed a tendency to have more severe crescent formation and less glomerulosclerosis, but the difference was not statistically significant. Endpoints such as death and ESKD were not significantly different between the two groups. CONCLUSIONS: Immune deposition may indicate lower complement C3, more severe hematuria and glomerular lesions, milder tubular atrophy, and interstitial fibrosis, but it cannot predict the renal outcome.

Urinary Bladder Schistosomiasis Mimicking Neoplasm: A Case Report.

Schistosomiasis is a neglected disease that is prevalent in tropical and subtropical areas. A 20-year-old woman presented to the emergency room with a history of right flank pain and lower abdominal discomfort for one day, which coincided with the onset of menses. The patient did not provide any history of premenstrual hematuria. The physical examination revealed right costovertebral angle tenderness and was otherwise unremarkable. The urinalysis demonstrated a mild increase in red and white blood cells and no ova or parasite. The blood test was normal, except for eosinophilia. A right pedunculated intraluminal urinary bladder mass was detected by the computerized axial tomographic scan and ultrasonography, and after the transurethral resection of the mass, the patient was diagnosed with urinary schistosomiasis. The patient received two doses of oral praziquantel of 1200 mg every 12 h for one day. The cure was confirmed with a one-month post-treatment follow-up that revealed a normal urine microscope and eosinophil count. The S. haematobium infection should be evaluated as a possible cause of urinary bladder lesion in those who have travelled or lived in endemic areas.

Diagnostic and Therapeutic Challenges in a Patient with Ureteral Metastases from a Triple Negative Breast Cancer.

Metastatic ureteral tumors arising from a primary breast carcinoma are extremely rare. They present with hematuria and radiological findings compatible with obstructive ureteral phenomena. We present a case of an 87-year-old woman with a history of lymphoma and triple negative breast cancer (TNBC), during an emergency admission for peptic ulcer, developed macroscopic hematuria. Radiologic and endoscopic investigations revealed a remarkable stenosis at the lower segment of the right ureter, attributed to metastases from her breast carcinoma. We report this case with the aim to make both oncologists and urologists aware of this rare condition.

What happens after the kidney biopsy? The findings nephrologists should know.

BACKGROUND: Percutaneous kidney biopsies are important tools for the diagnosis of kidney diseases. Nephrologists must be familiar with the expected complications of the procedure to provide an adequate informed consent. Here, we present a quality improvement analysis that reviews the complication rate of percutaneous kidney biopsies performed over a 2-year period by nephrologists at a single center, and that tabulates the nature and timing of these events. METHODS: From a single center cohort, pre- and post-biopsy anthropomorphic and clinical measurements were collected. Post-biopsy complications were tracked and sorted into either major or minor complications. Statistical tests were used to analyze complication incidence across the pre- and post-biopsy measurements obtained. RESULTS: Of the 154 nephrologist-performed percutaneous native kidney biopsies, 2 biopsies (1.3%) were found to result in a major complication. Both major complications were detected within 4 hours of the biopsy. Analysis of the pre-biopsy and post-biopsy measurements found that the proportion of complications was higher in patients with hematuria prior to biopsy. It was also found that patients with complications were statistically younger and had fewer comorbidities. Under univariable analysis, older age was associated with a lower incidence rate ratio for complications. However, no pre-or-post biopsy measurement or characteristic had a statistically significant change in incidence rate ratio under multivariable analysis. CONCLUSIONS: Percutaneous kidney biopsies were found to be low risk when performed by nephrologists in this single center cohort. Consistent with past literature, life threatening major complications rarely occurred and were reliably identified within 4 hours of biopsy, suggesting that centers can consider reduced observation times without compromising patient safety. Minor complications, such as pain, were more likely to occur in younger, healthier patients, and in those with hematuria prior to biopsy. This extensive tabulation of all biopsy adverse events is the first of its kind and will be beneficial for nephrologists to inform discussions with patients about expectations and risk-benefit of this procedure.

The pathological and outcome characteristics of renal lesions in Crohn's disease.

BACKGROUND: The inflammatory bowel disease, containing Crohn's disease and ulcerative colitis, was rare in the population, especially in the complication of kidney disease. A few studies had found proteinuria played a potential indicator of inflammatory bowel disease occurrence and activity. This study aimed to better define the histopathologic spectrum and study the outcome of renal disease in Crohn's disease. METHODS: A retrospective study of 3557 Crohn's disease from January 1st, 2016 to July 1st, 2021 in the Sixth Affiliated Hospital of Sun Yat-sen University identified 20 (0.56% [20/3557]) patients who underwent kidney biopsy. All biopsy specimens were examined by standard procedures containing light microscopy, immunofluorescence, and electron microscopy. RESULTS: Twenty cases were shown in this review study. Subnephrotic proteinuria (30% [6 of 20]), persistent hematuria and proteinuria (25% [5 of 20]), and isolated hematuria with acanthocytes (25% [5 of 20]) were the main indications for kidney biopsy. The most common diagnosis was IgA nephropathy (70% [14/20]), followed by minimal change disease (10% [2/20]), acute interstitial nephritis (5% [1/20]), granulomatous interstitial nephritis (5% [1/20]), non-IgA mesangial proliferative nephritis (5% [1/20]) and thin basement membrane nephropathy (5% [1/20]). The Lee classification of IgA nephropathy was mostly II or III level. Glomerular mesangial hyperplasia was the most common pathologic manifestation according to the MEST-C Sore. After twelve-month treatment, the majority of patients turned to complete remission of renal disease by measuring proteinuria, while 3 patients still stayed in the relapse stage and 6 patients turned to partial remission by measuring hematuria. CONCLUSIONS: IgA nephropathy is the most common kidney biopsy diagnosis in Crohn's disease. Renal damage in Crohn's disease mainly involves the glomerulus, especially the mesangial matrix. After the treatment, proteinuria might be in remission, but hematuria remains.

[The glomerulus in all its states]. / Le glomérule dans tous ses états.

Glomerulonephritis are the result of an inflammatory hit to the glomerulus. They are rare and heterogeneous renal diseases. Each glomerular compartment can be affected. The clinical manifestations present with hematuria, proteinuria and/or impaired renal function, either isolated or combined. Two main clinico-biological syndromes are described: nephrotic syndrome and nephritic syndrome. The latter can present in a more severe form i.e. rapidly progressive glomerulonephritis with the worst prognosis. These different clinical pictures are related to specific glomerular lesions. Thus, podocytic damage is mainly responsible for nephrotic syndromes, mesangial damage is responsible for proteinuria and hematuria and, finally, endothelial damage is responsible for nephritic syndrome and rapidly progressive glomerulonephritis. Therapeutic approaches include non-specific measures, combining both life-style and pharmacological interventions with the aim to reduce risk factors, and specific measures with the use of different immunosuppressive agents.

: Les glomérulonéphrites sont des atteintes inflammatoires du glomérule. Il s'agit de pathologies rénales rares et hétérogènes. Tous les compartiments glomérulaires peuvent être touchés. Les répercussions cliniques sont diverses. Elles se manifestent par une hématurie, une protéinurie et/ou une altération de la fonction rénale, présente chacune de manière isolée ou combinée. Deux principaux syndromes clinico-biologiques sont décrits : le syndrome néphrotique et le syndrome néphritique. Au sein de cette dernière entité, on distingue une forme plus sévère, les glomérulonéphrites rapidement progressives grevées du plus mauvais pronostic. Ces différents tableaux cliniques sont en lien avec des lésions glomérulaires spécifiques. Ainsi, les atteintes podocytaires sont principalement responsables des syndromes néphrotiques, les atteintes mésangiales sont responsables de protéinurie et d'hématurie et les atteintes endothéliales sont responsables de syndromes néphritiques et de glomérulonéphrites rapidement progressives. Les approches thérapeutiques comprennent des mesures non spécifiques, hygiéno-diététiques et pharmacologiques, visant à réduire les différents facteurs de risque, et des mesures spécifiques avec l'utilisation de divers médicaments immunosuppresseurs.

The evolution of performing a kidney biopsy: a single center experience comparing native and transplant kidney biopsies performed by interventional radiologists and nephrologists.

BACKGROUND: Kidney biopsy is the most vital tool guiding a nephrologist in diagnosis and treatment of kidney disease. Over the last few years, we have seen an increasing number of kidney biopsies being performed by interventional radiologists. The goal of our study was to compare the adequacy and complication rates between kidney biopsies performed by interventional radiology versus nephrology.  METHODS : We performed a single center retrospective analysis of a total of all kidney biopsies performed at our Institution between 2015 and 2021. All biopsies were performed using real-time ultrasound. Patients were monitored for four hours post biopsy and repeat ultrasound or hemoglobin checks were done if clinically indicated. The entire cohort was divided into two groups (Interventional radiology (IR) vs nephrology) based on who performed the biopsy. Baseline characteristics, comorbidities, blood counts, blood pressure, adequacy of the biopsy specimen and complication rates were recorded. Multivariable logistic regression was used to compare complication rates (microscopic hematuria, gross hematuria and need for blood transfusion combined) between these two groups, controlling for covariates of interest. ANCOVA (analysis of variance, controlling for covariates) was used to compare differences in biopsy adequacy (number of glomeruli per biopsy procedure) between the groups. RESULTS: 446 kidney biopsies were performed in the study period (229 native and 147 transplant kidney biopsies) of which 324 were performed by IR and 122 by nephrologist. There was a significantly greater number of core samples obtained by IR (mean = 3.59, std.dev. = 1.49) compared to nephrology (mean = 2.47, std.dev = 0.79), p < 0.0001. IR used 18-gauge biopsy needles while nephrologist exclusively used 16-gauge needles. IR used moderate sedation (95.99%) or general anesthesia (1.85%) for the procedures more often than nephrology, which used them only in 0.82% and 0.82% of cases respectively (p < 0.0001). Trainees (residents or fellows) participated in the biopsy procedures more often in nephrology compared to IR (97.4% versus 69.04%, p < 0.0001). The most frequent complication identified was microscopic hematuria which occurred in 6.8% of biopsies. For native biopsies only, there was no significant difference in likelihood of complication between groups, after adjustment for covariates of interest (OR = 1.01, C.I. = (0.42, 2.41), p = 0.99). For native biopsies only, there was no significant difference in mean number of glomeruli obtained per biopsy procedure between groups, after adjustment for covariates of interest (F(1,251) = 0.40, p = 0.53). CONCLUSION: Our results suggest that there is no significant difference in the adequacy or complication rates between kidney biopsies performed by IR or nephrology. This conclusion may indicate that kidney biopsies can be performed safely with adequate results either by IR or nephrologists depending on each institution's resources and expertise.

Explainable Biomarkers for Automated Glomerular and Patient-Level Disease Classification.

Pathologists use multiple microscopy modalities to assess renal biopsy specimens. Besides usual diagnostic features, some changes are too subtle to be properly defined. Computational approaches have the potential to systematically quantitate subvisual clues, provide pathogenetic insight, and link to clinical outcomes. To this end, a proof-of-principle study is presented demonstrating that explainable biomarkers through machine learning can distinguish between glomerular disorders at the light-microscopy level. The proposed system used image analysis techniques and extracted 233 explainable biomarkers related to color, morphology, and microstructural texture. Traditional machine learning was then used to classify minimal change disease (MCD), membranous nephropathy (MN), and thin basement membrane nephropathy (TBMN) diseases on a glomerular and patient-level basis. The final model combined the Gini feature importance set and linear discriminant analysis classifier. Six morphologic (nuclei-to-glomerular tuft area, nuclei-to-glomerular area, glomerular tuft thickness greater than ten, glomerular tuft thickness greater than three, total glomerular tuft thickness, and glomerular circularity) and four microstructural texture features (luminal contrast using wavelets, nuclei energy using wavelets, nuclei variance using color vector LBP, and glomerular correlation using GLCM) were, together, the best performing biomarkers. Accuracies of 77% and 87% were obtained for glomerular and patient-level classification, respectively. Computational methods, using explainable glomerular biomarkers, have diagnostic value and are compatible with our existing knowledge of disease pathogenesis. Furthermore, this algorithm can be applied to clinical datasets for novel prognostic and mechanistic biomarker discovery.