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Introduction: Membranoproliferative glomerulonephritis (MPGN) is a rare glomerular disease with a variable prognosis. A new classification based on the presence or absence of immunoglobulins and complement deposits in immunofluorescence microscopy (IF) of kidney biopsy has recently been proposed. The objectives of the study were to determine and compare the clinical, laboratory, and histopathological characteristics of those with primary or secondary MPGN, reclassify the primary ones based on IF findings, and evaluate kidney outcomes. Methods: This was an observational retrospective cohort study carried out in a single center (UNIFESP), based on the data collected from medical records of patients followed from 1996 to 2019. Results: Of 53 cases of MPGN, 36 (67.9%) were classified as primary and 17 (32.1%) as secondary MPGN. Most patients were hypertensive (84.9%) and had edema (88.7%) and anemia (84.9%); 33 (91.7%) patients classified as primary MPGN were reclassified as immune-complex-mediated and 3 (8.3%) as complement-mediated. The secondary MPGN group had hematuria more frequently (p

The most common HCV-related nephropathy is glomerulonephritis (MPGN), usually in the context of cryoglobulinaemia. The treatment of this entity is not consensual and represents a challenge to clinicians. We report a case of membranoproliferative glomerulonephritis associated with type II in a 46-year-old Caucasian male recipient of a deceased kidney transplant in 2010. His baseline serum creatinine (SCr) was 1.1 mg/dl. After three years post-transplantation, he presented with nephritic syndrome in association with renal function impairment (SCr - 2.1 mg/dl). The laboratory tests revealed positive rheumatoid factor, hypocomplementaemia and a positive cryocrit with type II cryoglobulinaemia. Antinuclear autoantibodies and anti-double stranded DNA antibodies were negative. Despite the presence of anti-HCV antibodies, the viral load remained undetectable. The allograft biopsy showed lesions compatible with membranoproliferative , with staining in the immunofluorescence for granular IgM and C3 and no C4d. He was treated with methylprednisolone pulses followed by oral prednisolone in association with rituximab. Two months after the last dose of rituximab, the SCr improved to 1.27 mg/dl, the proteinuria decreased and serum C3 levels normalized. Cryogloglobulins and rheumatoid factor became negative and HCV RNA remained undetectable. The patient was lost for follow-up. In our case, the treatment with rituximab resulted in a favourable outcome, although a longer follow-up period may be needed to evaluate the clinical response, since other studies reported high relapse rates. A glomerulonefrite membranoproliferativa com crioglobulinemia associa-se frequentemente à infeção pelo vírus da hepatite C. O tratamento desta entidade não é consensual e representa um desafio para os clínicos. Apresentamos um caso de glomerulonefrite membranoproliferativa associada a crioglobulinemia tipo II num doente do sexo masculino de 46 anos portador de enxerto renal de dador cadavérico desde 2010. O seu valor de creatinina sérico (SCr) era 1,1 mg/dl. Após 3 anos do transplante o paciente apresentou-se com síndrome nefrítico em associação com agravamento da função renal (SCr - 2,1 mg/dl). Os exames laboratoriais demonstraram: fator reumatoide positivo, crioglobulinemia tipo II, hipocomplementemia. Os anticorpos antinuclear e anti-double stranded DNA foram negativos. Apesar da presença de anticorpos anti-HCV a carga vírica era indetectável. A biópsia do enxerto renal demonstrou lesões compatíveis com glomerulonefrite membranoproliferativa com depósitos granulares para IgM e C3 e marcação com C4d negativa na imunofluorescência. Iniciou terapêutica com pulsos de metilprednisolona seguido posteriormente por prednisolona oral em associação com rituximab. Dois meses após a última dose de Rituximab o valor de creatinina melhorou para 1,27 mg/dl, a proteinúria diminuiu e os níveis de C3 normalizaram. O doseamento de crioglobulinas e de fator reumatoide foi negativo e a carga vírica do VHC permaneceu indetectável. Foi perdido o follow-up do doente. No nosso caso o tratamento com Rituximab associou-se a uma melhoria clínica. Um período de follow-up maior é necessário para a monitorização clínica uma vez que as taxas de recidiva são elevadas de acordo com estudos publicados na literatura.