A case of inflammatory myopathy with anti‐PM/Scl antibodies myopathologically presenting as polymyositis with mitochondrial pathology

We describe a rare case of inflammatory myopathy with anti‐PM/Scl antibodies myopathologically presenting as polymyositis with mitochondrial pathology (PM‐Mito). A 74‐year‐old Japanese man developed only slowly progressive proximal dominant muscle weakness and atrophy of the four extremities over th...

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Published inNeurology and clinical neuroscience Vol. 8; no. 5; pp. 335 - 339
Main Authors Matsumoto, Arifumi, Izumi, Rumiko, Sugeno, Naoto, Suzuki, Naoki, Namatame, Chihiro, Soga, Temma, Nishiyama, Ayumi, Kuroda, Hiroshi, Aoki, Masashi, Nagano, Isao
Format Journal Article
LanguageEnglish
Published Tokyo Wiley Subscription Services, Inc 01.09.2020
Subjects
Antibodies
Antigens
anti‐PM/Scl antibody
Atrophy
Autoimmune diseases
Biopsy
CD8 antigen
Creatine
Creatine kinase
Cytochrome-c oxidase
inclusion body myositis
Inflammation
Inflammatory diseases
Major histocompatibility complex
Mitochondria
Musculoskeletal diseases
Myopathy
Myositis
PM‐Mito
Polymyositis
Systemic sclerosis
Tacrolimus
Vacuoles
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Summary:We describe a rare case of inflammatory myopathy with anti‐PM/Scl antibodies myopathologically presenting as polymyositis with mitochondrial pathology (PM‐Mito). A 74‐year‐old Japanese man developed only slowly progressive proximal dominant muscle weakness and atrophy of the four extremities over the past 3 years. His serum creatine kinase level was moderately elevated, and anti‐PM/Scl‐75 antibodies were present. Systemic sclerosis and other systemic autoimmune diseases were not detected. Muscle biopsy revealed endomysial CD8‐positive T‐cell infiltration with diffuse upregulation of major histocompatibility complex class I antigens, few necrotic and regenerative changes atypical for polymyositis, few rimmed vacuoles and protein aggregates atypical for sporadic inclusion body myositis, and an excess of cytochrome C oxidase‐negative muscle fibers reflecting mitochondrial dysfunction. The elevated serum creatine kinase level decreased to the normal range following the initiation of oral tacrolimus treatment. PM‐Mito should be considered as one of the background myopathologies of inflammatory myopathy with anti‐PM/Scl antibodies.
ISSN:2049-4173
2049-4173
DOI:10.1111/ncn3.12429