ABSTRACT
Collapsing glomerulopathy (CG) is a rare entity as a glomerular disease. Although it has been considered as a variant of focal segmental glomerulosclerosis, the fact is that the podocyte lesions show different features with respect to the typical focal segmental glomerulosclerosis, an aspect that has been attributed to a type of podocytopathy. In CG, the podocyte lesion is typically characterised by a dysregulated podocyte phenotype, reflected by the loss of expression of mature podocyte markers. CG can be a primary disease or it can be associated with several causal factors that develop a common histopathological entity. The clinical expressiveness of CG is often characterised by the presence of a nephrotic syndrome and a rapid deterioration of the renal function than other variants of the focal segmental glomerulosclerosis. The prognosis of these patients is a rapid progression towards end-stage renal disease with poor response to treatment.
Subject(s)
Glomerulonephritis , Diagnosis, Differential , Glomerulonephritis/diagnosis , Glomerulonephritis/etiology , Glomerulonephritis/physiopathology , Glomerulonephritis/therapy , Glomerulosclerosis, Focal Segmental/diagnosis , Glomerulosclerosis, Focal Segmental/etiology , Glomerulosclerosis, Focal Segmental/physiopathology , Glomerulosclerosis, Focal Segmental/therapy , Humans , Kidney Failure, Chronic/diagnosis , Kidney Failure, Chronic/etiology , Kidney Failure, Chronic/physiopathology , Kidney Failure, Chronic/therapy , Nephrotic Syndrome/diagnosis , Nephrotic Syndrome/etiology , Nephrotic Syndrome/physiopathology , Nephrotic Syndrome/therapy , Prognosis , Risk FactorsABSTRACT
El lupus eritematoso sistémico (LES) es una enfermedad sistémica autoinmune que puede afectar a múltiples órganos. Aproximadamente el 50% de los pacientes con LES desarrollan enfermedad renal clínicamente evidente, la cual es una causa importante de morbimortalidad. El síndrome nefrótico (SN) es frecuente en los pacientes con nefritis lúpica (NL) y usualmente se asocia a depósitos de complejos inmunes en las paredes capilares, acompañados de proliferación endocapilar y necrosis. No obstante, existe un número creciente de casos reportados de pacientes con LES y SN cuyas biopsias se caracterizan por injuria podocitaria, consistente en fusión pedicelar en la microscopía electrónica y un patrón morfológico idéntico a la enfermedad por cambios mínimos (ECM), a la esclerosis focal y segmentaria primaria o a una glomerulonefritis proliferativa mesangial, en ausencia de depósitos inmunes en las paredes capilares. Este hallazgo podría deberse a la coexistencia de NL y ECM, sin embargo, la mayoría de las investigaciones consideran que esto no es una mera coincidencia. De allí surge una nueva entidad, la "podocitopatía lúpica", patología posiblemente mediada por la activación de células T y la presencia de un factor de permeación glomerular. Esto permite diferenciar al grupo de pacientes con LES y SN, que en la biopsia carecen de depósitos inmunes en las paredes capilares o de signos de actividad lúpica renal, se evidencia fusión pedicelar difusa en la ME y presentan además una alta sensibilidad al tratamiento con corticoides. El diagnóstico de esta nueva entidad, requiere de la interpretación de los hallazgos histopatológicos con la correcta integración de los datos de la inmunofluorescencia y la microscopía electrónica
Lupus Erythematosus (SLE) is a systemic autoimmune disease which may affect several organs. Approximately 50% of SLE patients develop clinically overt renal disease, an important cause of morbidity and mortality. Nephrotic syndrome (NS) is frequent in patients suffering from lupus nephritis (LN) and it is usually associated with immune complex deposition on capillary walls accompanied by endocapillary proliferation and necrosis. However, a growing number of reported cases of SLE and NS patients show biopsies which reveal podocyte injury, consisting of pedicel fusion upon electron microscopy and a morphological pattern identical to minimal change disease (MCD), primary focal segmental glomerulosclerosis or mesangial proliferative glomerulonephritis, in absence of immune complex deposition on capillary walls. Although this finding could be explained by the coexistence of LN and MCD, most researchers consider that this fact is not pure coincidence. A new term, lupus podocytopathy, therefore appears to define a distinct entity characterized by T cell activation and the presence of a glomerular permeability factor. This allows to distinguish the group of SLE and NS patients whose biopsies do not show immune complex deposition on capillary walls or signs of renal lupus activity; electron microscopy reveals diffuse pedicel fusion and patients show high responsiveness to corticosteroid treatment. In order to diagnose this new entity, it is necessary to interpret histopathological findings together with data gathered from immunofluorescence and electron microscopy
