[Renal involvement in monoclonal gammopathies]. / Compromiso renal en gammapatías monoclonales.

INTRODUCTION: The kidney is one of the organs most frequently affected by disease processes which produce monoclonal immunoglobins, therefore renal morphological and immunopathological alterations should be clearly recognized. OBJECTIVE: To describe the pathological features of renal involvement in monoclonal gammopathies. MATERIAL AND METHODS: A descriptive, retrospective and cross-sectional study of renal biopsies studied in a single center during a period of 14 years was carried out. RESULTS: 102 cases were included, of which 53% were male patients and the median age was 62.5 years (range 34 - 79). 97% of the biopsies were from native kidneys. The most frequent histopathological diagnosis (31.4%) was myeloma kidney, with kappa being the light chain most frequently deposited (65.6% of cases). AL amyloidosis was the second most common (29.4%) where the lambda chain predominated in 86.6%, followed by light chain deposition disease (20.6%) with the predominance of the kappa chain in 66.6%. CONCLUSIONS: The most frequent renal involvement due to monoclonal gammopathies was myeloma kidney with deposition of kappa light chains, followed by AL lambda amyloidosis; these diseases were found more frequently in patients over 50 years of age.

[The relevance of electron microscopy in kidney biopsies to 21st century pathology]. / Microscopía electrónica en biopsias renales: una evaluación de su utilidad en el siglo XXI.

INTRODUCTION: Electron microscopy (EM) has been used in the study of renal biopsies for more than 5 decades; however, it is expensive and the possibility of restricting it to selected cases has been considered. This study aims to reevaluate the necessity for EM in the diagnosis of renal biopsies today. MATERIAL AND METHODS: All renal biopsies taken between 2016 and 2019 with adequate light microscopy (LM), immunofluorescence (IF) and EM studies were included. The initial diagnosis (without EM) and the final diagnosis (with EM) was recorded. EM was considered necessary in cases in which the initial and final diagnoses did not concur, when diagnosis could not be made with LM and IF only or if the EM study revealed further clinically relevant findings. RESULTS: A total of 621 biopsies were included, 498 (80.2%) of native kidneys and 123 (19.8%) of transplanted kidneys. In 115 cases (18.5%) EM had been deemed necessary for diagnosis; it was required more frequently in hereditary diseases (96.8%) and isolated hematuria (88.9%) but less often in nephrotic syndrome (6.7%) and renal transplant biopsy (5.7%) (p < 0.001). CONCLUSIONS: EM was required in less than a fifth of renal biopsies, being more necessary in isolated hematuria and hereditary diseases and less so in nephrotic syndrome and in renal graft biopsies. These findings may prove useful as a guide to case selection protocols in which EM could be considered as a non-mandatory technique.

Compromiso renal en gammapatías monoclonales / Renal involvement in monoclonal gammopathies

Introducción: El riñón es uno de los órganos más comprometidos en enfermedades con producción de inmunoglobulinas monoclonales, por lo que es de gran importancia caracterizar muy bien las alteraciones morfológicas e inmunopatológicas en dicho compromiso. Objetivo: Describir las características del compromiso renal en gammapatías monoclonales desde una perspectiva anatomopatológica. Material y métodos: Se realizó un estudio descriptivo, retrospectivo y transversal, recolectándose biopsias renales estudiadas en un único centro durante un período de 14 años. Resultados: Se incluyeron 102 casos provenientes de 102 pacientes, el 53% de sexo masculino, la mediana de la edad fue 62,5 años (rango 34-79). El diagnóstico histopatológico más frecuente fue riñón de mieloma (31,4% de los casos), siendo kappa la cadena ligera más frecuentemente depositada (65,6% de casos), seguido de amiloidosis AL (29,4%), donde predominó la cadena lambda en un 86,6% y la enfermedad por depósitos de cadenas ligeras (20,6%) con predominio de la cadena kappa: 66,6%. El 97% de las biopsias fueron de riñón nativo. Conclusiones: El compromiso renal por gammapatías monoclonales más frecuente fue el riñón de mieloma con depósito de cadenas ligeras kappa, seguida de la amiloidosis AL lambda; estas enfermedades se encontraron con mayor frecuencia en pacientes mayores de 50 años de edad.(AU)

Introduction: The kidney is one of the organs most frequently affected by disease processes which produce monoclonal immunoglobins, therefore renal morphological and immunopathological alterations should be clearly recognized. Objective: To describe the pathological features of renal involvement in monoclonal gammopathies. Material and methods: A descriptive, retrospective and cross-sectional study of renal biopsies studied in a single center during a period of 14 years was carried out. Results: 102 cases were included, of which 53% were male patients and the median age was 62.5 years (range 34 - 79). 97% of the biopsies were from native kidneys. The most frequent histopathological diagnosis (31.4%) was myeloma kidney, with kappa being the light chain most frequently deposited (65.6% of cases). AL amyloidosis was the second most common (29.4%) where the lambda chain predominated in 86.6%, followed by light chain deposition disease (20.6%) with the predominance of the kappa chain in 66.6%. Conclusions: The most frequent renal involvement due to monoclonal gammopathies was myeloma kidney with deposition of kappa light chains, followed by AL lambda amyloidosis; these diseases were found more frequently in patients over 50 years of age.(AU)

Glomerulonefritis C3: una nueva categoría de glomerulonefritis con implicaciones etiopatogénicas / C3 glomerulonephritis: a new category of glomerulonephritis with etiopathogenic implications / Glomerulonefrite C3: uma nova categoria de glomerulonefrite com envolvimentos etiopatogênicas

Introducción: las glomerulonefritis con depósitos exclusivos de la fracción C3 del complemento (GN-C3) pueden implicar alteración en la vía alterna de este. Objetivos: describir retrospectivamente una serie de casos de GN-C3 y determinar la frecuencia con que los pacientes continúan con alteraciones renales y/o hipocomplementemia. Métodos: se evaluaron las características histológicas y clínicas y la evolución de los 22 casos de GN-C3 diagnosticados entre 2004 y 2012 en el Departamento de Patología (Facultad de Medicina, Universidad de Antioquia). Resultados: 14 de los pacientes fueron niños y 12 fueron hombres; la mediana de edad fue de 13 años (rango: 3-65). Diez se presentaron como síndrome nefrítico, siete como GN rápidamente progresiva, tres como insuficiencia renal aguda, uno como insuficiencia renal crónica y uno como síndrome nefrótico-nefrítico; 21 tenían hipocomplementemia C3. Todas las biopsias mostraron GN proliferativa. Ocho pacientes tuvieron remisión completa; cuatro, alteraciones persistentes del uroanálisis; seis desarrollaron enfermedad renal crónica, en cinco de ellos terminal; en cuatro no hubo seguimiento. En nueve pacientes hubo seguimiento de los niveles séricos de C3 y en todos ellos se normalizaron entre 1 y 3 meses después de la biopsia. Conclusiones: las GN-C3 pueden producir alteraciones renales persistentes o recurrentes y evolucionar a la insuficiencia renal terminal. Es recomendable el seguimiento clínico a largo plazo, con mediciones repetidas de los niveles de C3.

Introduction: Glomerulonephritis with only deposits of C3 (GN-C3) could involve alteration on the complement alternative pathway. Objective: To describe retrospectively a series of GNC3 cases and to determine the frequency with which patients continue with renal alterations and/or hypocomplementemia. Methods: The 22 cases of GN-C3 diagnosed between 2004 and 2012 at the Department of Pathology, Faculty of Medicine, University of Antioquia (Medellin, Colombia) were included. Their histological and clinical characteristics and their outcome were evaluated. Results: 14 patients were children and 12 were males. Mean age was 13 years (range: 3-65). Ten presented as a nephritic syndrome, seven as a rapidly progressive GN, three as acute renal failure, one as chronic renal failure, and one as a nephrotic-nephritic syndrome. The C3 fraction of complement was low in 21 cases. All biopsies showed proliferative GN. There was complete remission in eight patients, persistent urinalysis alterations in four, chronic renal failure in six, five of them end-stage. No follow-up was done in four. In nine patients follow-up determination of C3 serum levels was done; in all of them they normalized between 1 to 3 months after biopsy. Conclusions: GN-C3 can produce persistent or recurrent kidney alterations and end-stage renal disease. Long-term follow-up with repeated determinations of C3 is advisable.

Introdução: as glomerulonefrite com depósitos exclusivos da fração C3 do complemento (GN-C3) podem implicar alteração na via alterna deste. Objetivos: descrever retrospectivamente uma série de casos de GN-C3 e determinar a frequência com que os pacientes continuam com alterações renais e/ ou hipocomplementemia. Métodos: avaliaram-se as características histológicas e clínicas e a evolução dos 22 casos de GN-C3 diagnosticados entre 2004 e 2012 no Departamento de Patologia (Faculdade de Medicina, Universidade de Antioquia). Resultados: 14 dos pacientes foram meninos e 12 foram homens; a média de idade foi de 13 anos (casta: 3-65). Dez se apresentaram como síndrome nefrítico, sete como GN rapidamente progressiva, três como insuficiência renal aguda, um como insuficiência renal crônica e um como síndrome nefrótico-nefrítico; 21 tinham hipocomplementemia C3. Todas as biopsias mostraram GN proliferativa. Oito pacientes tiveram remissão completa; quatro, alterações persistentes do uroanálise; seis desenvolveram doença renal crônica, em cinco deles terminal; em quatro não teve seguimento. Em nove pacientes teve seguimento dos níveis séricos de C3 e em todos eles se normalizaram entre 1 e 3 meses depois da biopsia. Conclusões: as GN-C3 podem produzir alterações renais persistentes.