title: A case of endocapillary proliferative glomerulonephritis with macrophages phagocytosing monoclonal immunoglobulin lambda light chain.
abstract: Multiple myeloma (MM) is a plasma-cell neoplasm that can cause renal disorders. Renal lesions in MM can present with a very rare pathological manifestation involving a specific monoclonal immunoglobulin (Ig). We report the case of a 33-year-old woman who had edema, fatigue, elevated serum creatinine levels, hypoalbuminemia, and hypercholesterolemia. She had persistent hematuria and proteinuria lasting 3 years. Serum protein electrophoresis showed an M-spike, and serum immunofixation demonstrated the presence of monoclonal IgG λ. She had proteinuria in the nephrotic range, and a monoclonal λ fragment was present on urine immunofixation. Renal biopsy showed proliferative glomerulonephritis with λ light chain and C3c deposition and inflammatory cell infiltration with CD68. Macrophage lysosomes contained λ light chains, suggesting their partial phagocytosis. She was diagnosed with symptomatic MM and was treated with bortezomib and dexamethasone and an autologous peripheral stem cell transplant conditioned with intravenous melphalan. She achieved a partial response with decreased serum monoclonal protein and improved renal function. This case may be categorized as a monoclonal gammopathy-associated proliferative glomerulonephritis. The biopsy finding of partially phagocytosed Ig λ light chains by macrophages is very rare; this pathological condition is similar to crystal-storing histiocytosis.
authors.affiliation: Division of Clinical Nephrology and Rheumatology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Watanabe
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Osawa
authors.forename: Shin
authors.initials: S
authors.lastname: Goto
authors.forename: Masato
authors.initials: M
authors.lastname: Habuka
authors.forename: Naofumi
authors.initials: N
authors.lastname: Imai
authors.forename: Yumi
authors.initials: Y
authors.lastname: Ito
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hirose
authors.forename: Takaaki
authors.initials: T
authors.lastname: Chou
authors.forename: Ryuji
authors.initials: R
authors.lastname: Ohashi
authors.forename: Akira
authors.initials: A
authors.lastname: Shimizu
authors.forename: Takashi
authors.initials: T
authors.lastname: Ehara
authors.forename: Takashi
authors.initials: T
authors.lastname: Shimotori
authors.forename: Ichiei
authors.initials: I
authors.lastname: Narita
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal; D005260:Female; D005921:Glomerulonephritis / Q000276:immunology*; D006801:Humans; D007146:Immunoglobulin lambda-Chains / Q000276:immunology*; D008264:Macrophages / Q000276:immunology*; D009101:Multiple Myeloma / Q000150:complications / Q000276:immunology*; D010265:Paraproteinemias / Q000276:immunology; D010587:Phagocytosis / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D007146:Immunoglobulin lambda-Chains
keywords: crystal-storing histiocytosis; endocapillary hypercellularity; membranoproliferative glomerulonephritis; monoclonal gammopathy-associated proliferative glomerulonephritis; multiple myeloma