title: [Glomerulopathies with organized monoclonal immunoglobulin deposits].
abstract: The spectrum of glomerular disorders with organized immunoglobulin (Ig) deposits is heterogeneous. It encompasses 2 mains categories: glomerulopathies with fibrillary deposits are mostly represented by immunoglobulinic amyloidosis (most commonly AL amyloidosis, characterized by monoclonal light chain deposits often of the lambda isotype), and pseudo-amyloid fibrillary glomerulonephritis in which deposits predominantly contain polyclonal IgG4. Glomerulopathies with microtubular deposits include cryoglobulinemic glomerulonephritis (type I and type II, with or without detectable serum cryoglobulin) and glomerulonephritis with organized microtubular monoclonal Ig deposits (GOMMID) also referred to as immunotactoid glomerulopathy. Pathological diagnosis requires meticulous studies by light microscopy (with systematic Congo red staining), immunofluorescence with specific conjugates, and electron microscopy. Ultrastructural studies are required to differentiate amyloid fibrils (8 to 10 nm in external diameter), pseudo-amyloid fibrils (15-20 nm) and microtubules (10 to 50 nm in external diameter, with a central hollow core). Glomerular deposits in type I cryoglobulinemic glomerulonephritis are arranged into parallel straight microtubules similar to those observed in GOMMID, but with different topography that allows distinction between the two entities. Glomerular substructures composed of circulating Igs should be distinguished from collagen fibrils that are commonly observed in glomerular disorders with or without deposition of monoclonal or polyclonal Igs.
authors.affiliation: Service de néphrologie-hémodialyse-transplantation rénale, service d'anatomie pathologique et unité de pathologie ultrastructurale, Centre de référence national maladies rares : amylose AL et autres maladies de dépôts d'immunoglobulines monoclonales, hôpital Jean-Bernard, 2, rue de la Milétrie, 86021 Poitiers cedex, France; CNRS UMR 6101, 87000 Limoges, France; Inserm unité 927, CHU, 86021 Poitiers cedex, France. Electronic address: g.touchard@chu-poitiers.fr.
authors.forename: Guy
authors.initials: G
authors.lastname: Touchard
authors.affiliation: Service de néphrologie-hémodialyse-transplantation rénale, service d'anatomie pathologique et unité de pathologie ultrastructurale, Centre de référence national maladies rares : amylose AL et autres maladies de dépôts d'immunoglobulines monoclonales, hôpital Jean-Bernard, 2, rue de la Milétrie, 86021 Poitiers cedex, France; CNRS UMR 6101, 87000 Limoges, France; Inserm unité 927, CHU, 86021 Poitiers cedex, France.
authors.forename: Frank
authors.initials: F
authors.lastname: Bridoux
authors.affiliation: Service de néphrologie-hémodialyse-transplantation rénale, service d'anatomie pathologique et unité de pathologie ultrastructurale, Centre de référence national maladies rares : amylose AL et autres maladies de dépôts d'immunoglobulines monoclonales, hôpital Jean-Bernard, 2, rue de la Milétrie, 86021 Poitiers cedex, France; CNRS UMR 6101, 87000 Limoges, France; Inserm unité 927, CHU, 86021 Poitiers cedex, France.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Goujon
mesh_terms: D005921:Glomerulonephritis / Q000276:immunology* / Q000473:pathology / Q000628:therapy; D006801:Humans; D007136:Immunoglobulins / Q000378:metabolism*; D007678:Kidney Glomerulus / Q000473:pathology; D008854:Microscopy, Electron
chemical_list: D007136:Immunoglobulins
keywords: Amylose; Cryoglobulinemia; Cryoglobulines; Dépôts organisés; Electronic microscopy; Fibrillar; Fibrilles; Glomerulonephritis; Glomérulonéphrite; Immunoglobulines; Immunoglobulins; Microscopie électronique; Microtubules; Organised deposits