title: C5b-9 deposits on endomysial capillaries in non-dermatomyositis cases.
abstract: Deposits of the terminal-membrane-attack-complex (MAC) C5b-9 on perfascicular endomysial capillaries are generally regarded as diagnostic hallmark of dermatomyositis (DM). Although the pathophysiology is not clear, C5b-9 deposits on capillaries seem to be associated with microinfarctions and vascular damage. Here, we report on a series of 19 patients presenting with C5b-9 accumulation on endomysial capillaries in the absence of features for DM. To decipher differences in the capillary C5b-9 accumulation pattern between DM and non-DM cases, we assessed the extent of endomysial capillary C5b-9 deposits related to capillary density and extent of myofiber necrosis by immunohistochemistry in 12 DM and 8 control patients. We found similar numbers of C5b-9-positive myofibers in both DM and non-DM C5b-9(+) cases. The distribution pattern differed as DM cases showed significantly more perifascicular capillary C5b-9 deposits as compared to non-DM cases, which presented stronger endomysial capillary C5b-9 deposits in a diffuse pattern. While total capillary density was not differing, DM patients displayed significantly more C5b-9(+) necrotic fibers as compared to non-DM C5b-9(+). In summary, endomysial capillary C5b-9 deposits are present in a variety of non-DM cases, however with differing distribution pattern. In conclusion, capillary C5b-9(+) deposits should be assessed critically, taking into consideration the distribution pattern.
authors.affiliation: Edinger Institute, Institute of Neurology, University of Frankfurt am Main, Germany.
authors.forename: Anne K
authors.initials: AK
authors.lastname: Braczynski
authors.affiliation: Edinger Institute, Institute of Neurology, University of Frankfurt am Main, Germany.
authors.forename: Patrick N
authors.initials: PN
authors.lastname: Harter
authors.affiliation: Edinger Institute, Institute of Neurology, University of Frankfurt am Main, Germany.
authors.forename: Pia S
authors.initials: PS
authors.lastname: Zeiner
authors.affiliation: Edinger Institute, Institute of Neurology, University of Frankfurt am Main, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Drott
authors.affiliation: Edinger Institute, Institute of Neurology, University of Frankfurt am Main, Germany.
authors.forename: Dominique-Suzanne
authors.initials: DS
authors.lastname: Tews
authors.affiliation: Department of Neuropathology, Charité, Berlin, Germany.
authors.forename: Corinna
authors.initials: C
authors.lastname: Preusse
authors.affiliation: Edinger Institute, Institute of Neurology, University of Frankfurt am Main, Germany.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Penski
authors.affiliation: Edinger Institute, Institute of Neurology, University of Frankfurt am Main, Germany.
authors.forename: Maika
authors.initials: M
authors.lastname: Dunst
authors.affiliation: Institute of Neuropathology, RWTH, Aachen, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Weis
authors.affiliation: Department of Neuropathology, Charité, Berlin, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Stenzel
authors.affiliation: Edinger Institute, Institute of Neurology, University of Frankfurt am Main, Germany. Electronic address: michel.mittelbronn@kgu.de.
authors.forename: Michel
authors.initials: M
authors.lastname: Mittelbronn
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D002196:Capillaries / Q000378:metabolism* / Q000473:pathology*; D015938:Complement Membrane Attack Complex / Q000378:metabolism*; D003882:Dermatomyositis / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007154:Immune System Diseases / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D009210:Myofibrils / Q000378:metabolism / Q000473:pathology; D009336:Necrosis / Q000378:metabolism / Q000473:pathology; D011446:Prospective Studies; D012680:Sensitivity and Specificity
chemical_list: D015938:Complement Membrane Attack Complex
keywords: C5b-9; Dermatomyositis; MHC-I; Microvascular unit; Muscle disease