A case of multicentric Castleman's disease with membranoproliferative glomerulonephritis type 3-like lesion.

Renal involvement is a significant complication of multicentric Castleman's disease (MCD) and various glomerular involvements have been reported. A 45-year-old Japanese man presented with persistent proteinuria, with lymphadenopathy and hypergammaglobulinemia. He had been diagnosed 4 years previously with MCD. As his renal impairment had progressed to renal failure, he underwent a renal biopsy. Histology revealed diffuse and global membranous lesions with large and heterogeneous epimembranous deposits. In addition, mesangial cell proliferation and focal extracapillary lesions were found. Under immunofluorescence, granular staining for anti-IgG, IgG1, IgG2 and IgA was strongly positive in the capillary loop, and weakly positive in the mesangium. As such, there was a diversity of histological features. Our perspective with regard to pathogenesis is that the formation of the immune-complex contributed to the membranoproliferative glomerulonephritis type 3-like lesion. This histological multiform with MCD is valuable for increasing our understanding of the mechanism for onset of immune-complex glomerular deposition and cellular proliferation of glomerulonephritis.