title: A case of amyloid myopathy diagnosed during the treatment of myopathy associated with anti-signal recognition particle antibodies.
abstract: A 78-year-old man presented with subacute progressive proximal weakness and dysphagia. A biopsy specimen from the left biceps femoris revealed evidence of necrotic and regenerating muscle fibers, but lymphocyte infiltration was not noted. The patient was diagnosed with necrotizing myopathy with anti-signal recognition particle (SRP) antibodies. Concomitant therapy with prednisolone and azathioprine caused the serum CK level to return to normal and it caused clinical manifestations to abate. One year later, however, muscle weakness worsened. Immunoelectrophoresis of serum revealed IgG M protein, and muscle pathology revealed amyloid deposits in numerous blood vessels and at the periphery of a few muscle fibers, and deposits stained positive for anti-λ light chain antibody. The patient was diagnosed with amyloid myopathy, and therapy for systemic amyloid light chain amyloidosis caused muscle weakness to diminish. Amyloidosis is believed to be the primary pathology in this case based on the patient's response to treatment reaction, but the significance of a case involving both amyloid myopathy and necrotizing myopathy warranted examination.
authors.affiliation: Department of Neurology, Shizuoka General Hospital.
authors.forename: Nobuko
authors.initials: N
authors.lastname: Kawakami
authors.affiliation: Department of Neurology, Shizuoka General Hospital.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Katsuyama
authors.affiliation: Department of Neurology, Shizuoka General Hospital.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Hagiwara
authors.affiliation: Department of Neurology, Shizuoka General Hospital.
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Yoshida
authors.affiliation: Department of Neurology, Shizuoka General Hospital.
authors.forename: Kang
authors.initials: K
authors.lastname: Kim
authors.affiliation: Department of Neurology, Shizuoka General Hospital.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Harada
mesh_terms: D000368:Aged; D000682:Amyloid / Q000378:metabolism; D000686:Amyloidosis / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D006023:Glycoproteins / Q000097:blood; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007146:Immunoglobulin lambda-Chains / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D008297:Male; D009132:Muscles / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D009135:Muscular Diseases / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology; D009336:Necrosis; D018271:Signal Recognition Particle / Q000276:immunology*; D016896:Treatment Outcome
chemical_list: D000682:Amyloid; D001323:Autoantibodies; D015415:Biomarkers; D006023:Glycoproteins; D007074:Immunoglobulin G; D007146:Immunoglobulin lambda-Chains; D018271:Signal Recognition Particle; C023587:protein M (glycoprotein)
keywords: IgG type; amyloidmyopathy; amyloidosis; anti-SRP antibody; necrotizing myopathy