title: Direct immunofluoresence in vasculitic neuropathy: specificity of vascular immune deposits.
abstract: In suspected vasculitic neuropathy, vasculitis is demonstrated in only 30% of superficial peroneal nerve (SPN)/peroneus brevis muscle (PBM) specimens. Pathologic predictors of vasculitis are thus needed for non-diagnostic cases. Immune deposits in epineurial vessels have an established sensitivity but unknown specificity. In this study we assessed specificity using direct immunofluorescence (DIF) in SPN/PBM biopsies for suspected vasculitic neuropathy. Biopsies from 13 patients with vasculitis, 13 without vasculitis, and 6 with diabetic radiculoplexus neuropathy (DRPN) were stained for immunoglobulin G (IgG), IgM, and complement 3 (C3), and analyzed in a blinded manner. Vascular immunoglobulin or C3 deposits occurred in 12 of 13 nerve or muscle biopsies (11 of 13 nerves, 5 of 13 muscles) in vasculitis vs. 1 of 13 (1 of 13 nerves, 0 of 13 muscles) in controls (P = 0.00003). Specificity was 92%. For DRPN, vascular immune deposits occurred in 5 of 6 nerves or muscles (4 of 6 nerves, 1 of 5 muscles), similar to vasculitis but significantly different from controls. Epineurial/perimysial vascular deposits of immunoglobulin/C3 by DIF are a specific marker of vasculitic neuropathy.
authors.affiliation: Department of Neurology, Medical College of Wisconsin, 9200 West Wisconsin Avenue, Milwaukee, Wisconsin 53226, USA. mcollins@mcw.edu
authors.forename: Michael P
authors.initials: MP
authors.lastname: Collins
authors.forename: Isabel
authors.initials: I
authors.lastname: Periquet-Collins
authors.forename: Zarife
authors.initials: Z
authors.lastname: Sahenk
authors.forename: John T
authors.initials: JT
authors.lastname: Kissel
mesh_terms: D000368:Aged; D001706:Biopsy; D015331:Cohort Studies; D003176:Complement C3 / Q000737:chemistry*; D003929:Diabetic Neuropathies / Q000473:pathology; D005260:Female; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry*; D007075:Immunoglobulin M / Q000737:chemistry*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000098:blood supply / Q000294:innervation / Q000473:pathology; D010523:Peripheral Nervous System Diseases / Q000276:immunology / Q000473:pathology*; D010543:Peroneal Nerve / Q000473:pathology; D012039:Regional Blood Flow / Q000502:physiology; D014657:Vasculitis / Q000276:immunology / Q000473:pathology*
chemical_list: D003176:Complement C3; D007074:Immunoglobulin G; D007075:Immunoglobulin M