- Immune complex mediated – MPGN is secondary to an underlying chronic infection, autoimmune disease, or monoclonal gammopathy that leads to antigenemia and/or circulating immune complexes that deposit in the mesangium. Common infectious causes include hepatitis B or C, bacterial endocarditis, or parasitic infections. Common autoimmune causes include systemic lupus erythematosus, Sjögren syndrome, or rheumatoid arthritis. Patients with monoclonal gammopathy, such as monoclonal gammopathy of undetermined significance (MGUS) or multiple myeloma, may present with proteinuria and worsening renal function.
- Complement mediated – Less common than immune-mediated MPGN; due to dysregulation and persistent activation of the alternative complement pathway leading to deposition of complement products along the capillary walls and in the mesangium with bright C3 staining in these locations. Diseases include dense deposit disease (DDD), in which damage results from antibodies that bind to C3 convertase; it is seen in both adults and children. Patients with C3 glomerulonephritis (C3GN) present with proteinuria, hematuria, and hypertension from over-activation of the complement cascade due to mutations in complement regulatory genes. This disease often progresses to end-stage renal disease and can recur after transplantation.
N05.5 – Unspecified nephritic syndrome with diffuse mesangiocapillary glomerulonephritis
80321008 – Mesangiocapillary glomerulonephritis