ABSTRACT
Introducción: La nefropatía membranosa (NM) es la causa más frecuente de síndrome nefrótico en adultos. El diagnóstico se basa en los hallazgos típicos observados con el microscopio electrónico (ME) y el estudio de inmunofluorescencia (IF). En algunas ocasiones, sólo se dispone de tejido para estudio de microscopio óptico (MO); en estos casos puede ser complicado diferenciar entre una NM y una enfermedad por cambios mínimos (ECM). Recientemente se está extendiendo el estudio con C4d por inmunohistoquímica. Existe muy poca información sobre el depósito de C4d en la NM. Nuestro estudio consistió en analizar si el depósito de C4d realizado en la muestra en parafina podría ser útil en el diagnóstico de NM. Material y métodos: Estudio retrospectivo que incluyó a todos los pacientes diagnosticados de NM mediante biopsia renal en nuestra unidad entre enero de 2001 y octubre de 2008. Se incluyeron sólo adultos con un diagnóstico certero de NM y ECM idiopática que dispusieran de estudios con MO, IF y ME. En octubre de 2008, secciones de 3 µm de tejido renal fijado en formaldehído fueron deparafinadas y rehidratadas. Después se tiñeron mediante inmunohistoquímica con C4d usando un anticuerpo policlonal antihumano obtenido de conejo. Resultados: Se incluyeron finalmente 19 pacientes con ECM y 21 con NM. Ningún depósito de C4d fue observado en ninguno de los glomérulos de los pacientes con ECM y el 100% de estos pacientes fueron clasificados como negativos. Sin embargo, el depósito de C4d se detectó en el 100% de los pacientes con NM y en todos los glomérulos con una distribución uniforme y granular dibujando todas las asas capilares. Conclusiones: El depósito de C4d mediante inmunohistoquímica es una herramienta muy útil en el diagnóstico de NM (AU)
Introduction: membranous nephropathy (MN) is the most common cause of nephrotic syndrome in adults. The diagnosis is based on typical findings observed using electron microscope (EM) and immunofluorescence (IF) studies. On some occasions, tissues are only available for analysis using an optical microscope (OM); in these cases, it can be difficult to differentiate between MN and minimal change disease (MCD). Recently, the use of C4d immunohistochemical staining has spread. Very little information is available regarding C4d deposits in MN. Our study consisted of analysing whether C4d staining of samples embedded in paraffin could be useful for diagnosing MN. Material and Method: Ours was a retrospective study including all patients diagnosed with MN by renal biopsy in our unit between January 2001 and October 2008. We only included adult patients with a definitive diagnosis of MN or idiopathic MCD by OM, IF, and ME studies. In October 2008, 3µm sections of renal tissue fixed in formaldehyde were removed from paraffin and rehydrated. The samples were then stained for C4d immunohistochemical analysis using anti-human polyclonal antibodies obtained from rabbits. Results: Our study included a final sample of 19 patients with MCD and 21 with MN. No C4d deposits were observed in any of the glomeruli in patients with MCD, and 100% of these patients were classified as negative. However, C4d deposits were detected in 100% of patients with MN, and were observable in all glomeruli with a uniform granular distribution, demarcating all capillary loops. Conclusions: C4d immunohistochemical staining is a very useful tool for diagnosing MN (AU)
Subject(s)
Humans , Glomerulonephritis, Membranous/diagnosis , Complement C4/analysis , Biomarkers/analysis , Nephrotic Syndrome/physiopathology , Retrospective Studies , BiopsyABSTRACT
INTRODUCTION: membranous nephropathy (MN) is the most common cause of nephrotic syndrome in adults. The diagnosis is based on typical findings observed using electron microscope (EM) and immunofluorescence (IF) studies. On some occasions, tissues are only available for analysis using an optical microscope (OM); in these cases, it can be difficult to differentiate between MN and minimal change disease (MCD). Recently, the use of C4d immunohistochemical staining has spread. Very little information is available regarding C4d deposits in MN. Our study consisted of analysing whether C4d staining of samples embedded in paraffin could be useful for diagnosing MN. MATERIAL AND METHOD: Ours was a retrospective study including all patients diagnosed with MN by renal biopsy in our unit between January 2001 and October 2008. We only included adult patients with a definitive diagnosis of MN or idiopathic MCD by OM, IF, and ME studies. In October 2008, 3µm sections of renal tissue fixed in formaldehyde were removed from paraffin and rehydrated. The samples were then stained for C4d immunohistochemical analysis using anti-human polyclonal antibodies obtained from rabbits. RESULTS: Our study included a final sample of 19 patients with MCD and 21 with MN. No C4d deposits were observed in any of the glomeruli in patients with MCD, and 100% of these patients were classified as negative. However, C4d deposits were detected in 100% of patients with MN, and were observable in all glomeruli with a uniform granular distribution, demarcating all capillary loops. CONCLUSIONS: C4d immunohistochemical staining is a very useful tool for diagnosing MN.
