Myeloperoxidase anti-cytoplasmic antibody related crescentic glomerulonephritis in a patient with IgG3λ monoclonal immunoglobulin deposition disease with membranous features.

A 68-year-old woman showed rapidly progressive glomerulonephritis based on the fact that she had 1+ proteinuria (1.1 g/day), a 3+ occult blood reaction, blood urea nitrogen of 32.4 mg/dL, serum creatinine of 2.96 mg/dL, and myeloperoxidase (MPO)-anti-neutrophil cytoplasmic antibodies (ANCA) at 52 ELISA Unit (normal range: below 10). A renal biopsy demonstrated a bubbling appearance associated with cellular crescent formation with segmental necrosis. Immunofluorescence studies showed granular IgG3λ deposition along the basement membrane and in the mesangial area. This is the first English-language case report describing MPO-ANCA positive crescentic glomerulonephritis in a patient demonstrating monoclonal immunoglobulin deposition disease with mainly membranous features.