title: Muscle biopsy features of idiopathic inflammatory myopathies and differential diagnosis.
abstract: The gold standard to characterize idiopathic inflammatory myopathies is the morphological, immunohistochemical and immunopathological analysis of muscle biopsy. Mononuclear cell infiltrates and muscle fiber necrosis are commonly shared histopathological features. Inflammatory cells that surround, invade and destroy healthy muscle fibers expressing MHC class I antigen are the typical pathological finding of polymyositis. Perifascicular atrophy and microangiopathy strongly support a diagnosis of dermatomyositis. Randomly distributed necrotic muscle fibers without mononuclear cell infiltrates represent the histopathological hallmark of immune-mediated necrotizing myopathy; meanwhile, endomysial inflammation and muscle fiber degeneration are the two main pathological features in sporadic inclusion body myositis. A correct differential diagnosis requires immunopathological analysis of the muscle biopsy and has important clinical implications for therapeutic approach. In particular, unnecessary, potentially harmful, immune-suppressive therapy should be avoided alike in dystrophic myopathies with secondary inflammation.
authors.affiliation: Department of Neurological and Movement Sciences, Section of Clinical Neurology, University of Verona, Verona, Italy.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Vattemi
authors.affiliation: Istituto di Neurologia-Policlinico "A. Gemelli", Università Cattolica, Rome, Italy.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Mirabella
authors.affiliation: Department of Neurological and Movement Sciences, Section of Clinical Neurology, University of Verona, Verona, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Guglielmi
authors.affiliation: Istituto di Neurologia-Policlinico "A. Gemelli", Università Cattolica, Rome, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Lucchini
authors.affiliation: Department of Neurological and Movement Sciences, Section of Clinical Neurology, University of Verona, Verona, Italy.
authors.forename: Giuliano
authors.initials: G
authors.lastname: Tomelleri
authors.affiliation: Division of Rheumatology, Department of Medicine, University of Padua, Via Giustiniani, 35128 PADOVA, Padua, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Ghirardello
authors.affiliation: Division of Rheumatology, Department of Medicine, University of Padua, Via Giustiniani, 35128 PADOVA, Padua, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Doria
keywords: Autoimmune myositis; Differential diagnosis; Histopathology; Inflammatory myopathy