Elsa Guiard

Patterns of noncryoglobulinemic glomerulonephritis with monoclonal Ig deposits: correlation with IgG subclass and response to rituximab.

BACKGROUND AND OBJECTIVES Several different entities have recently been described among glomerular diseases associated with monoclonal IgG deposits. The aim of this study was to describe the distribution of the different pathologic subtypes of IgG-associated glomerulopathy and to evaluate the IgG isotype involved in these diseases. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This was a retrospective study including all patients with glomerular deposits of monoclonal IgG referred to three nephrology departments between 1980 and 2008. RESULTS Twenty-six patients were included. Nephrotic syndrome was almost constantly associated with a renal dysfunction in 14 of 26 patients. The presence of M-spike was detected in only 30% of the patients, and an overt hematologic malignancy (myeloma, lymphoma) was identified in 9 of 26 patients. Patients were almost equally divided into two distinct histologic patterns: membranous nephropathy (MN) or membranoproliferative glomerulonephritis (MPGN). IgG3 deposits were identified in 80% of patients with MPGN, whereas IgG1 deposits were present in 64% of patients with MN. Ultrastructural study showed that immune deposits were nonorganized in most patients. Seven patients were treated with rituximab with excellent results: five of seven had a complete remission of the nephrotic syndrome and two of seven had a partial response. After a mean 24-month follow-up, only one patient experienced relapse of the nephropathy. CONCLUSIONS GN with monoclonal Ig deposits can be associated with MPGN or MN, which are correlated with IgG3 and IgG1 isotypes, respectively. Rituximab appears to have a very favorable benefit-to-risk ratio for patients with no overt hematologic malignancy.

Mise au pointGranulomatose avec polyangéite (maladie de Wegener)Granulomatosis with polyangiitis (Wegener's granulomatosis)

Granulomatosis with polyangiitis (GPA), is the recently proposed, new alternative name for Wegeners granulomatosis. It defines a systemic small-vessels vasculitis, characterized by frequent involvement of upper and lower respiratory tract. The presence of cytoplasmic-type ANCA with anti-proteinase 3 specificity is observed in more than 90% of patients with GPA but is not mandatory for the definition of the disease, which is based on clinical criteria and presence of granulomas on the tissue biopsy. Necrotizing glomerulonephritis is observed in more than 50% of patients, and has important prognostic value, requiring urgent therapeutic intervention. Classical immunosuppressive schemes used in GPA combine high-dose corticosteroids and cyclophosphamide, but recent trials have shown that rituximab offers a similar efficacy with probably less cytotoxic side-effects. The best maintenance treatment is not yet defined, but the prevention of relapses remains the main therapeutic challenge in this vasculitis.