title: Correlation of clinicoserologic and pathologic classifications of inflammatory myopathies: study of 178 cases and guidelines for diagnosis.
abstract: The idiopathic inflammatory myopathies (IIM) are acquired muscle diseases characterized by muscle weakness and inflammation on muscle biopsy. Clinicoserologic classifications do not take muscle histology into account to distinguish the subsets of IIM. Our objective was to determine the pathologic features of each serologic subset of IIM and to correlate muscle biopsy results with the clinicoserologic classification defined by Troyanov et al, and with the final diagnoses. We retrospectively studied a cohort of 178 patients with clinicopathologic features suggestive of IIM with the exclusion of inclusion body myositis. At the end of follow-up, 156 of 178 cases were still categorized as IIM: pure dermatomyositis, n = 44; pure polymyositis, n = 14; overlap myositis, n = 68; necrotizing autoimmune myopathy, n = 8; cancer-associated myositis, n = 18; and unclassified IIM, n = 4. The diagnosis of IIM was ruled out in the 22 remaining cases. Pathologic dermatomyositis was the most frequent histologic picture in all serologic subsets of IIM, with the exception of patients with anti-Ku or anti-SRP autoantibodies, suggesting that it supports the histologic diagnosis of pure dermatomyositis, but also myositis of connective tissue diseases and cancer-associated myositis. Unspecified myositis was the second most frequent histologic pattern. It frequently correlated with overlap myositis, especially with anti-Ku or anti-PM-Scl autoantibodies. Pathologic polymyositis was rare and more frequently correlated with myositis mimickers than true polymyositis. The current study shows that clinicoserologic and pathologic data are complementary and must be taken into account when classifying patients with IIM patients. We propose guidelines for diagnosis according to both clinicoserologic and pathologic classifications, to be used in clinical practice.
authors.affiliation: From the Department of Pathology and Neuropathology (CF, AMdP, JFP, DFB); Department of Neurology and Neuromuscular Diseases (ESC, JF, JP), Centre de référence des maladies neuromusculaires; and Department of Internal Medicine (AB, PJW); Hôpital Timone, AP-HM, Marseille; Department of Immunology (NB) and Department of Internal Medicine (NS), Hôpital de la Conception, AP-HM, Marseille; France.
authors.forename: Carla
authors.initials: C
authors.lastname: Fernandez
authors.forename: Nathalie
authors.initials: N
authors.lastname: Bardin
authors.forename: André Maues
authors.initials: AM
authors.lastname: De Paula
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Salort-Campana
authors.forename: Audrey
authors.initials: A
authors.lastname: Benyamine
authors.forename: Jérôme
authors.initials: J
authors.lastname: Franques
authors.forename: Nicolas
authors.initials: N
authors.lastname: Schleinitz
authors.forename: Pierre-Jean
authors.initials: PJ
authors.lastname: Weiller
authors.forename: Jean
authors.initials: J
authors.lastname: Pouget
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Pellissier
authors.forename: Dominique
authors.initials: D
authors.lastname: Figarella-Branger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies / Q000097:blood; D001706:Biopsy; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D017408:Guidelines as Topic; D006801:Humans; D008297:Male; D008875:Middle Aged; D009220:Myositis / Q000097:blood / Q000473:pathology*; D012189:Retrospective Studies
chemical_list: D001323:Autoantibodies