title: Inclusion body myositis with granuloma formation in muscle tissue.
abstract: Inclusion body myositis is a form of inflammatory myopathy. We identified 4 cases of inclusion body myositis showing granuloma formation in muscle tissue and aimed to assess the features of this atypical form of inclusion body myositis. We retrospectively reviewed consecutive patients who satisfied European Neuromuscular Centre IBM Research Diagnostic Criteria 2011. Then, we assessed clinical profiles and pathological findings in patients with inclusion body myositis with granuloma and compared these findings with those of typical inclusion body myositis without granuloma. We identified 15 patients with inclusion body myositis. Four patients showed granuloma formation in muscle tissue in addition to typical pathological features of inclusion body myositis. Granulomas comprised a mixture of inflammatory cells, such as macrophages, epithelioid histiocytic cells, and lymphocytes. One patient was found to have mediastinal granulomatous lymphadenopathy; however, the evidence in other patients was insufficient for a diagnosis of systemic sarcoidosis. There were no significant differences between groups with and without granuloma regarding clinical manifestations, laboratory findings, response to immunomodulating therapies, or myopathological profiles. We established a new form of inclusion body myositis showing granuloma formation in muscle tissue. Inclusion body myositis and granuloma formation could have identical pathomechanisms concerning dysregulation of autophagy.
authors.affiliation: Department of Neurology and Neurobiology of Aging, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan. Electronic address: ksakai@med.kanazawa-u.ac.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Sakai
authors.affiliation: Department of Neurology and Neurobiology of Aging, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan; Department of Neurology, National Hospital Organization Iou Hospital, Kanazawa, Japan.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Ikeda
authors.affiliation: Department of Neurology and Neurobiology of Aging, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan; Department of Neurology, National Hospital Organization Iou Hospital, Kanazawa, Japan.
authors.forename: Chiho
authors.initials: C
authors.lastname: Ishida
authors.affiliation: Department of Neurology and Neurobiology of Aging, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan; Department of Neurology, Ishikawa Prefectural Central Hospital, Kanazawa, Japan.
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Matsumoto
authors.affiliation: Department of Neurology and Neurobiology of Aging, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan.
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Ono
authors.affiliation: Department of Neurology and Neurobiology of Aging, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Iwasa
authors.affiliation: Department of Neurology and Neurobiology of Aging, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan.
authors.forename: Masahito
authors.initials: M
authors.lastname: Yamada
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015622:Epithelioid Cells / Q000473:pathology; D005260:Female; D006099:Granuloma / Q000150:complications*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology; D018979:Myositis, Inclusion Body / Q000150:complications* / Q000473:pathology*; D012189:Retrospective Studies
keywords: Autophagy; Granuloma; Inclusion body myositis; Rimmed vacuole