title: Polymyositis with cytochrome C oxidase negative fibers--a pathological and clinical challenge.
abstract: Polymyositis (PM) with cytochrome C oxidase negative fibers also referred to as PM with mitochondrial pathology (PM-Mito) is characterized by the symptoms of inclusion body myositis (IBM) and by the myopathological findings of PM except for an increase of muscle fibers with insufficient mitochondrial cytochrome C oxidase activity. Few PM-Mito cases are published; mitochondrial ultrastructure has not been studied in these patients. We report 2 PM-Mito patients with later onset than usually seen in IBM and poor responsiveness to glucocorticoids. Electron microscopy of muscle fibers showed irregular mitochondrial ultrastructure. Sjögren syndrome related antinuclear antibodies (Anti-Ro and Anti-La) were found in one of the two patients but the typical clinical symptoms of Sjögren syndrome such as xerostomia and keratoconjunctivitis were absent in this patient. Taken together, our observations, viewed in conjunction with the current literature, suggest that PM-Mito is an underdiagnosed disease with a multifactorial pathogenesis that should be elucidated in further studies. We want to encourage clinicians and pathologists to consider the possibility of PM-Mito in patients with atypical PM or sIBM.
authors.affiliation: Department of Neurology, University Hospital Carl Gustav Carus, Dresden University of Technology, Dresden, Germany. timo.siepmann@uniklinikum-dresden.de
authors.forename: Timo
authors.initials: T
authors.lastname: Siepmann
authors.forename: Manfred
authors.initials: M
authors.lastname: Tesch
authors.forename: Florian
authors.initials: F
authors.lastname: Krause
authors.forename: Ben Min-Woo
authors.initials: BM
authors.lastname: Illigens
authors.forename: Gisela
authors.initials: G
authors.lastname: Stoltenburg-Didinger
mesh_terms: D000368:Aged; D003576:Electron Transport Complex IV / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000648:ultrastructure*; D018485:Muscle Fibers, Skeletal / Q000201:enzymology* / Q000648:ultrastructure*; D017285:Polymyositis / Q000145:classification / Q000201:enzymology* / Q000473:pathology*
chemical_list: D003576:Electron Transport Complex IV