title: IgG4-related disease and idiopathic membranous nephropathy:  "The clothes do not make the man" .
abstract: This case report describes a patient with a previous history of autoimmune pancreatitis secondary to IgG4-related disease, who developed an overt nephrotic syndrome due to membranous nephropathy, surprisingly idiopathic. In all the previously described cases with both concurrent diseases, membranous nephropathy was considered to be secondary to the IgG4-related disease based on the absence of anti-PLA2R1 autoantibodies, and nephrotic syndrome usually remitted after treatment with steroids alone. However, in our patient positivity of serum anti-PLA2R1 autoantibodies together with a normal serum IgG4 level, and the absence of the other most commonly associated diseases were compatible with an idiopathic membranous nephropathy. Combination treatment with steroids and cyclophosphamide was successful. We hypothesize about causality or coincidental diseases and the importance of a correct classification. .
authors.forename: Mercedes
authors.initials: M
authors.lastname: Acevedo Ribó
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Ahijado Hormigos
authors.forename: Francisco
authors.initials: F
authors.lastname: Díaz
authors.forename: Marta
authors.initials: M
authors.lastname: Romero Molina
authors.forename: Maria Angeles
authors.initials: MA
authors.lastname: Fernandez Rojo
authors.forename: Maria Antonia
authors.initials: MA
authors.lastname: Garcia Rubiales
authors.forename: Eugenio
authors.initials: E
authors.lastname: García Diaz
mesh_terms: D001323:Autoantibodies / Q000097:blood; D001327:Autoimmune Diseases / Q000150:complications*; D015433:Glomerulonephritis, Membranous / Q000150:complications*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008875:Middle Aged; D009404:Nephrotic Syndrome / Q000188:drug therapy / Q000209:etiology*; D010195:Pancreatitis / Q000150:complications*; D054507:Receptors, Phospholipase A2 / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D007074:Immunoglobulin G; C516360:PLA2R1 protein, human; D054507:Receptors, Phospholipase A2