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.

Membranous nephropathy.

Membranous nephropathy is a glomerulopathy, which main affected target is the podocyte, and has consequences on the glomerular basement membrane. It is more common in adults, especially over 50 years of age. The clinical presentation is nephrotic syndrome, but many cases can evolve with asymptomatic non-nephrotic proteinuria. The mechanism consists of the deposition of immune complexes in the subepithelial space of the glomerular capillary loop with subsequent activation of the complement system. Great advances in the identification of potential target antigens have occurred in the last twenty years, and the main one is the protein "M-type phospholipase-A2 receptor" (PLA2R) with the circulating anti-PLA2R antibody, which makes it possible to evaluate the activity and prognosis of this nephropathy. This route of injury corresponds to approximately 70% to 80% of cases of membranous nephropathy characterized as primary. In the last 10 years, several other potential target antigens have been identified. This review proposes to present clinical, etiopathogenic and therapeutic aspects of membranous nephropathy in a didactic manner, including cases that occur during kidney transplantation.

Rituximab therapy for childhood onset idiopathic nephrotic syndrome: experience of a Portuguese tertiary center.

INTRODUCTION: Rituximab (RTX) is a therapeutic option in pediatric difficult-to-treat idiopathic nephrotic syndrome (NS). We aimed to assess the efficacy and safety of RTX use in these patients. METHOD: A retrospective study of all patients with idiopathic NS treated with RTX was conducted in a pediatric nephrology division of a tertiary hospital. Demographic, anthropometric, clinical and analytical data were collected prior to treatment and at 6, 12, and 24 months. RESULTS: Sixteen patients were included (11 males), with a median (25th-75th percentile, P25-P75) age at diagnosis of 2 (2.0-2.8) years. Fifteen were steroid-sensitive and 1 was steroid-resistant and sensitive to cyclosporine. The median age at administration of RTX was 10 (6.3-14.0) years. Throughout a median follow-up time of 2.5 (1.0-3.0) years, 6 (37.5%) patients achieved partial remission and 7 (43.8%) had no relapses and were not taking any immunosuppressants at the 24-month follow-up visit. Regarding complications, 1 patient presented persistent hypogammaglobulinemia. Compared with the 12-month period before RTX, there was a decrease in the median number of relapses at 6 and 12 months [3 (3.0-4.0) vs 0 (0-0.8) and 0.50 (0-1.0), respectively; p = 0.001] and in the daily steroids dose (mg/kg/day) at 6, 12, and 24 months [0.29 (0.15-0.67)vs [0.10 (0.07-0.13); p = 0.001], [0.12 (0.05-0.22); p = 0.005] and [0.07(0.04-0.18); p = 0.021]], respectively. There was also a reduction in the median BMI z score at 24 months [2.11 (0.45-3.70) vs. 2.93 (2.01-3.98); p = 0.049]. CONCLUSION: Our results confirm the efficacy and safety of RTX use in pediatric idiopathic NS and highlight its' potential cardiometabolic benefits.

Congenital Nephrotic Syndrome of the Finnish Type in a Dominican Newborn: An Overview and Case Report.

Congenital nephrotic syndrome of the Finnish type (CNS-FT) is a rare genetic condition that causes massive proteinuria, hypoproteinemia, hypercholesterolemia, and edema that progresses to end-stage renal disease. Symptoms may manifest in utero as fetal hydrops or during the first few days to months of life. This article shares the case of a Dominican infant who presented with CNS-FT. It provides a comprehensive overview of CNS-FT including the underlying genetic cause, prenatal and postnatal diagnostic testing options, and treatment recommendations. It walks the reader through the diagnostic and initial and longer-term management of this infant and provides patient outcome at 10 months of age.

[Development of nephrotic syndrome in a patient with Hashimoto's Thyroiditis]. / Desarrollo de Síndrome nefrótico en paciente con Tiroiditis de Hashimoto.

The development of nephrotic syndrome in concomitance with Hashimoto's thyroiditis is an in frequent association in the pediatric age. OBJECTIVE: To report an infrequent complication of au toimmune thyroiditis, such as the appearance of nephrotic syndrome. CLINICAL CASE: A 10-year-old patient presenting with nephrotic syndrome and goiter. A history of autoimmune thyroiditis and un treated hypothyroidism was detected. Corticosteroid and hormone replacement therapy (levothyro- xine) is started, achieving a good clinical and laboratory response. CONCLUSION: Autoimmune thyroi ditis impacts renal physiology through immunological and non-immunological mechanisms. At the same time, renal repercussions can affect thyroid function. The importance of this communication lies in reporting an infrequent complication of autoimmune thyroiditis, such as the appearance of nephrotic syndrome.

Nefropatía por inmunoglobulina M: características histopatológicas y clínicas. Serie de casos / Immunoglobulin M nephropathy: histopathological and clinical characteristics. Case series

La nefropatía por inmunoglobulina M (NIgM) es una glomerulopatía idiopática caracterizada por depósitos mesangiales globales y difusos de IgM. Se realizó un estudio retrospectivo de las características clínicas e histopatológicas de los pacientes con NIgM atendidos en nuestro servicio. De 241 biopsias renales, 21 correspondieron a NIgM (8,7 %). Se incluyeron 18 pacientes (14 de sexo femenino, mediana de edad: 3,08 años). Se excluyó a 1 paciente por enfermedad sistémica asociada y a 2 por seguimiento menor a 1 año. Catorce pacientes se manifestaron con síndrome nefrótico (SN) y 4 con proteinuria aislada o asociada a hematuria. En la microscopia óptica, 13 presentaron hiperplasia mesangial, y 5 esclerosis focal y segmentaria. De los pacientes con SN, 7 fueron corticorresistentes, 4 corticodependientes y 3 presentaban recaídas frecuentes. Todos los pacientes con SN y 1 con proteinuria-hematuria recibieron inmunosupresores; los 18 pacientes recibieron, además, antiproteinúricos. Luego de 5,2 años (2-17,5) de seguimiento, 6 pacientes evolucionaron a enfermedad renal crónica

Immunoglobulin M nephropathy (IgMN) is an idiopathic glomerulopathy characterized by diffuse global mesangial deposits of IgM. We retrospectively studied the clinical and histopathological characteristics of the patients with IgMN seen in our service. Of 241 renal biopsies, 21 corresponded to IgMN (8.7 %). One patient was excluded due to associated systemic disease and 2 due to follow-up less than 1 year, 18 were included (14 girls, median age 3.08 years). Fourteen manifested with nephrotic syndrome (NS) and the remaining with proteinuria (isolated or associated with hematuria). On light microscopy, 13 had hyperplasia with mesangial expansion and 5 had focal and segmental sclerosis. Of the patients with NS, 7 were steroid-resistant, 4 steroid-dependent, and 3 frequent relapsers. All patients with NS and 1 with proteinuria-hematuria received immunosuppressants; the 18 patients also received antiproteinuric drugs. After 5.2 years (2-17.5) of follow-up, 6 patients developed chronic kidney disease.

COVID-19 associated with onset nephrotic syndrome in a pediatric patient: coincidence or related conditions?

BACKGROUND: COVID-19 is less frequent in children than in adults and affects the former less severely; despite the fact that respiratory symptoms are the most frequent, in some cases unusual manifestations can be seen. CASE-DIAGNOSIS: We present a 15-year-old boy who tested positive for SARS-COV-2 infection and onset of nephrotic syndrome, without antecedent of kidney disease and who had normal urine tests shortly before being affected by COVID-19. CONCLUSIONS: The patient described in this report, who was admitted due to nephrotic syndrome and respiratory syndrome, tested positive for COVID-19. He, based on the data review by the researchers, is the first reported case of COVID-19 with simultaneous onset of complete picture of nephrotic syndrome. The presence of both diagnoses could be a coincidence or an unusual form of presentation of COVID-19.

Urinary cytology: a potential tool for differential diagnosis of acute kidney injury in patients with nephrotic syndrome.

OBJECTIVE: Acute tubular necrosis (ATN) is a frequent cause of acute kidney injury (AKI). In patients with nephrotic syndrome (NS), AKI demands the differential diagnosis between ATN and rapidly progressive glomerulonephritis. In some cases, conclusive diagnosis is possible only by kidney biopsy. We aimed to study the potential use of urine cytology in the differential diagnosis between ATN and proliferative glomerular lesion in patients with NS. RESULTS: Cell size analysis showed a higher proportion of small cells and a lower proportion of large cells in the urine of patients with AKI. Cells phenotypes were easily defined using cytological preparations. Leukocytes were found to be a primary classifier of NS groups, with higher number in patients with AKI and patients with proliferative glomerular lesions. Although renal biopsy is still required for confirmative diagnosis, our data suggests that urinary cytology can be readily performed and support the differential diagnosis between proliferative glomerular lesion and ATN in patients with NS and AKI.

Non-lupus full house nephropathy in pediatrics: Case reports / Nefropatía full house no lúpica en pediatría: reporte de dos casos.

Full house nephropathy is defined as the simultaneous detection of IgA, IgG, IgM, C3, and C1q deposits by immunofluorescence, usually indicating lupus nephritis. There are patients with this immunofluorescence pattern, but with negative autoantibody serology, which means they cannot be diagnosed with systemic lupus erythematosus. Patients presenting with full house nephropathy but no other criteria for lupus are diagnosed as having nonlupus full house nephropathy. Here, we describe two cases: A male patient who debuted with rapidly progressive glomerulonephritis and a female patient with nephrotic syndrome. Both had negative autoantibody serology, findings in the renal biopsy of class IV lupus nephritis and afull house immunofluorescence pattern. Histological findings in non-lupus full house nephropathy are similar to those in lupus nephritis and, probably, similar physiopathological bases. However, prospective studies are needed to determine risk factors and the renal prognosis and to make suggestions for specific treatments.

La nefropatía full house se refiere a la detección simultánea de depósitos de IgA, IgG, IgM, C3 y C1q en la inmunofluorescencia, lo que generalmente indica la presencia de nefritis lúpica. Hay pacientes con este patrón de inmunofluorescencia, pero con serología negativa para autoanticuerpos, por lo que no se les puede diagnosticar un lupus eritematoso sistémico. Este tipo de nefropatía, en la que no se presentan otros criterios para lupus, se denomina nefropatía full house no lúpica. En esta presentación, se describen dos casos: un paciente que ingresó con una glomerulonefritis rápidamente progresiva y una paciente con síndrome nefrótico, ambos con serología negativa para autoanticuerpos, hallazgos en la biopsia renal indicativos de nefritis lúpica de clase IV y un patrón full house en la inmunofluorescencia. La nefropatía full house no lúpica tiene rasgos histológicos similares a los de la nefritis lúpica y, probablemente, sus bases fisiopatológicas son parecidas. Sin embargo, se necesitan estudios prospectivos para conocer los factores de riesgo y el pronóstico renal, y poder hacer sugerencias sobre tratamientos específicos.

Una nueva mutación asociada con el síndrome de Pierson / A new mutation associated with Pierson syndrome

El síndrome de Pierson se caracteriza por la presencia de síndrome nefrótico congénito y microcoria bilateral. Genéticamente, este trastorno está ocasionado por mutaciones en el gen LAMB2, que codifica la cadenaß2 de la laminina. Hasta la fecha, en la bibliografía se informaron 98casos y 50mutaciones diferentes. No existen terapias específicas para el síndrome de Pierson, y el tratamiento es complementario. El pronóstico es malo por la disfunción renal progresiva y las complicaciones de la insuficiencia renal. En este artículo, se informa sobre una mutación homocigota novedosa (c.1890G>C [p.Q630H]) en el gen LAMB2 en una paciente con síndrome de Pierson que tenía un fenotipo atípico, como epidermólisis ampollosa.

Pierson syndrome is characterized by congenital nephrotic syndrome and bilateral microcoria. Genetically, mutations in the LAMB2 gene, which encodes the laminin ß2 chain, lead to this disorder. To date, 98 cases and 50 different mutations have been reported in literature. There are no specific therapies for Pierson syndrome and treatment is supportive. The prognosis is poor because of progressive impairment of renal function and complications of renal failure. We report a novel homozygous mutation (c.1890G>T, p.Q630H) in the LAMB2 gene in a patient with Pierson syndrome who had atypical phenotypic feature such as epidermolysis bullosa

A new mutation associated with Pierson syndrome. / Una nueva mutación asociada con el síndrome de Pierson.

Pierson syndrome is characterized by congenital nephrotic syndrome and bilateral microcoria. Genetically, mutations in the LAMB2 gene, which encodes the laminin ß2 chain, lead to this disorder. To date, 98 cases and 50 different mutations have been reported in literature. There are no specific therapies for Pierson syndrome and treatment is supportive. The prognosis is poor because of progressive impairment of renal function and complications of renal failure. We report a novel homozygous mutation (c.1890G>T, p.Q630H) in the LAMB2 gene in a patient with Pierson syndrome who had atypical phenotypic feature such as epidermolysis bullosa.

El síndrome de Pierson se caracteriza por la presencia de síndrome nefrótico congénito y microcoria bilateral. Genéticamente, este trastorno está ocasionado por mutaciones en el gen LAMB2, que codifica la cadena ß2 de la laminina. Hasta la fecha, en la bibliografía se informaron 98 casos y 50 mutaciones diferentes. No existen terapias específicas para el síndrome de Pierson, y el tratamiento es complementario. El pronóstico es malo por la disfunción renal progresiva y las complicaciones de la insuficiencia renal. En este artículo, se informa sobre una mutación homocigota novedosa (c.1890G>C [p.Q630H]) en el gen LAMB2 en una paciente con síndrome de Pierson que tenía un fenotipo atípico, como epidermólisis ampollosa.

Focal and Segmental Glomerulosclerosis and Membranous Nephropathy overlapping in a patient with Nephrotic Syndrome: a case report / Glomeruloesclerose Segmentar e Focal e Nefropatia Membranosa sobrepostas em paciente com Síndrome Nefrótica: relato de caso

Abstract Introduction: Some cases of membranous nephropathy (MGN) present focal segmental glomerulosclerosis (FSGS) typically associated with disease progression. However, we report a case of a patient who seemed to have MGN and FSGS, both primary. Case presentation: A 17-year-old female, Caucasian, presenting lower extremity edema associated with episodes of foamy urine and high blood pressure, had physical and laboratorial exams indicating nephrotic syndrome. A renal biopsy was performed and focal and segmental glomerulosclerosis were observed under light microscopy in some glomeruli presented as tip lesion, and in others it was accompanied by podocyte hypertrophy and podocyte detachment in urinary space, compatible with podocytopathy FSGS. Besides, there were thickened capillary loops with basement membrane irregularities due to "spikes" compatible with MGN stage II. Immunofluorescence showed finely granular IgG, IgG4, and PLA2R deposits in capillary loops and, in electron microscopy, subepithelial deposits and foot process effacement. These morphological findings are compatible with FSGS and MGN stage II. Conclusions: In the present case, clinical and morphological characteristics showed a possible overlap of primary FSGS and MGN as focal and segmental glomerulosclerosis does not seem to be related with MGN progression but with the podocytopathy FSGS.

Resumo Introdução: Alguns casos de nefropatia membranosa (NM) apresentam glomeruloesclerose segmentar e focal (GESF) tipicamente associada a progressão da doença. Contudo, relatamos o caso de uma paciente que parece ter NM e GESF, ambas primárias. Apresentação do caso: Uma jovem branca de 17 anos de idade com edema de membros inferiores associado a episódios de urina espumosa e hipertensão apresentou-se com achados físicos e laboratoriais sugestivos de síndrome nefrótica. Foi realizada biópsia renal. GESF foi observada por microscopia de luz em alguns glomérulos que apresentavam lesões de ponta, enquanto em outros o achado era acompanhado por hipertrofia podocitária e descolamento de podócitos no espaço urinário, compatíveis com podocitopatia GESF. Além disso, as alças capilares estavam espessadas com irregularidades na membrana basal devido a "espículas" compatíveis com NM estágio II. Imunofluorescência revelou depósitos finamente granulares de IgG, IgG4 e PLA2R nas alças capilares. Microscopia eletrônica exibiu depósitos subepiteliais e apagamento de pedicelos. Tais achados morfológicos são compatíveis com GESF e NM estágio II. Conclusões: No presente caso, as características clínicas e morfológicas revelaram uma possível sobreposição de GESF primária e NM, uma vez que a glomeruloesclerose segmentar e focal não parece estar relacionada com a progressão da NM, mas com a podocitopatia GESF.

Focal and Segmental Glomerulosclerosis and Membranous Nephropathy overlapping in a patient with Nephrotic Syndrome: a case report.

INTRODUCTION: Some cases of membranous nephropathy (MGN) present focal segmental glomerulosclerosis (FSGS) typically associated with disease progression. However, we report a case of a patient who seemed to have MGN and FSGS, both primary. CASE PRESENTATION: A 17-year-old female, Caucasian, presenting lower extremity edema associated with episodes of foamy urine and high blood pressure, had physical and laboratorial exams indicating nephrotic syndrome. A renal biopsy was performed and focal and segmental glomerulosclerosis were observed under light microscopy in some glomeruli presented as tip lesion, and in others it was accompanied by podocyte hypertrophy and podocyte detachment in urinary space, compatible with podocytopathy FSGS. Besides, there were thickened capillary loops with basement membrane irregularities due to "spikes" compatible with MGN stage II. Immunofluorescence showed finely granular IgG, IgG4, and PLA2R deposits in capillary loops and, in electron microscopy, subepithelial deposits and foot process effacement. These morphological findings are compatible with FSGS and MGN stage II. CONCLUSIONS: In the present case, clinical and morphological characteristics showed a possible overlap of primary FSGS and MGN as focal and segmental glomerulosclerosis does not seem to be related with MGN progression but with the podocytopathy FSGS.

Incidence and risk factors for major infections in hospitalized children with nephrotic syndrome / Incidência e fatores de risco para infecções graves em crianças hospitalizadas com síndrome nefróticas

ABSTRACT Introduction: Children with nephrotic syndrome are at increased risk of infections because of disease status itself and use of various immunosuppressive agents. In majority, infections trigger relapses requiring hospitalization with increased risk of morbidity and mortality. This study aimed to determine the incidence, spectrum, and risk factors for major infections in hospitalized children with nephrotic syndrome. Methods: All consecutive hospitalized children between 1-12 years of age with nephrotic syndrome were enrolled in the study. Children with acute nephritis, secondary nephrotic syndrome as well as those admitted for diagnostic renal biopsy and intravenous cyclophosphamide or rituximab infusion were excluded. Results: A total of 148 children with 162 admissions were enrolled. Incidence of major infections in hospitalized children with nephrotic syndrome was 43.8%. Peritonitis was the commonest infection (24%), followed by pneumonia (18%), urinary tract infection (15%), and cellulitis (14%), contributing with two thirds of major infections. Streptococcus pneumoniae (n = 9) was the predominant organism isolated in children with peritonitis and pneumonia. On logistic regression analysis, serum albumin < 1.5gm/dL was the only independent risk factor for all infections (OR 2.6; 95% CI, 1.2-6; p = 0.01), especially for peritonitis (OR 29; 95% CI, 3-270; p = 0.003). There were four deaths (2.5%) in our study, all due to sepsis and multiorgan failure. Conclusions: Infection remains an important cause of morbidity and mortality in children with nephrotic syndrome. As Pneumococcus was the most prevalent cause of infection in those children, attention should be paid to the pneumococcal immunization in children with nephrotic syndrome.

RESUMO Introdução: Crianças com síndrome nefrótica apresentam maior risco de infecções devido ao próprio status da doença e ao uso de vários agentes imunossupressores. Em grande parte, as infecções desencadeiam recidivas que exigem hospitalização, com risco aumentado de morbidade e mortalidade. Este estudo teve como objetivo determinar a incidência, o espectro e os fatores de risco para infecções graves em crianças hospitalizadas com síndrome nefrótica. Métodos: Todas as crianças hospitalizadas consecutivamente entre 1 e 12 anos de idade com síndrome nefrótica foram incluídas no estudo. Crianças com nefrite aguda, síndrome nefrótica secundária, bem como aquelas admitidas para biópsia renal diagnóstica e infusão intravenosa de ciclofosfamida ou rituximabe foram excluídas. Resultados: Foram cadastradas 148 crianças com 162 internações. A incidência de infecções graves em crianças hospitalizadas com síndrome nefrótica foi de 43,8%. A peritonite foi a infecção mais comum (24%), seguida por pneumonia (18%), infecção do trato urinário (15%) e celulite (14%), contribuindo com dois terços das principais infecções. Streptococcus pneumoniae (n = 9) foi o organismo predominantemente isolado em crianças com peritonite e pneumonia. Na análise de regressão logística, a albumina sérica < 1,5gm / dL foi o único fator de risco independente para todas as infecções (OR 2,6; 95% CI, 1,2-6; p = 0,01), especialmente para peritonite (OR 29; IC95% 3 -270, p = 0,003). Houve quatro mortes (2,5%) em nosso estudo, todas devido a sepse e falência de múltiplos órgãos. Conclusões: A infecção continua sendo uma importante causa de morbimortalidade em crianças com síndrome nefrótica. Como o Pneumococo foi a causa mais prevalente de infecção nessas crianças, deve-se atentar para a imunização pneumocócica em crianças com síndrome nefrótica.

Incidence and risk factors for major infections in hospitalized children with nephrotic syndrome.

INTRODUCTION: Children with nephrotic syndrome are at increased risk of infections because of disease status itself and use of various immunosuppressive agents. In majority, infections trigger relapses requiring hospitalization with increased risk of morbidity and mortality. This study aimed to determine the incidence, spectrum, and risk factors for major infections in hospitalized children with nephrotic syndrome. METHODS: All consecutive hospitalized children between 1-12 years of age with nephrotic syndrome were enrolled in the study. Children with acute nephritis, secondary nephrotic syndrome as well as those admitted for diagnostic renal biopsy and intravenous cyclophosphamide or rituximab infusion were excluded. RESULTS: A total of 148 children with 162 admissions were enrolled. Incidence of major infections in hospitalized children with nephrotic syndrome was 43.8%. Peritonitis was the commonest infection (24%), followed by pneumonia (18%), urinary tract infection (15%), and cellulitis (14%), contributing with two thirds of major infections. Streptococcus pneumoniae (n = 9) was the predominant organism isolated in children with peritonitis and pneumonia. On logistic regression analysis, serum albumin < 1.5gm/dL was the only independent risk factor for all infections (OR 2.6; 95% CI, 1.2-6; p = 0.01), especially for peritonitis (OR 29; 95% CI, 3-270; p = 0.003). There were four deaths (2.5%) in our study, all due to sepsis and multiorgan failure. CONCLUSIONS: Infection remains an important cause of morbidity and mortality in children with nephrotic syndrome. As Pneumococcus was the most prevalent cause of infection in those children, attention should be paid to the pneumococcal immunization in children with nephrotic syndrome.