title: Clinical assessment determines the diagnosis of inclusion body myositis independently of pathological features.
abstract: OBJECTIVE
  Historically, the diagnosis of sporadic inclusion body myositis (IBM) has required the demonstration of the presence of a number of histopathological findings on muscle biopsy--namely, rimmed vacuoles, an inflammatory infiltrate with invasion of non-necrotic muscle fibres (partial invasion) and amyloid or 15-18 nm tubulofilamentous inclusions (Griggs criteria). However, biopsies of many patients with clinically typical IBM do not show all of these histopathological findings, at least at presentation. We compared the clinical features at presentation and during the course of disease in 67 patients with histopathologically diagnosed IBM and clinically diagnosed IBM seen within a single UK specialist muscle centre.
  
  
  RESULTS
  At presentation, using clinically focused diagnostic criteria (European Neuromuscular Centre (ENMC) 2011), a diagnosis of IBM was made in 88% of patients whereas 76% fulfilled the 1997 ENMC criteria and only 27% satisfied the histopathologically focused Griggs criteria. There were no differences in clinical features or outcomes between clinically and histopathologically diagnosed patients, but patients lacking the classical histopathological finding of rimmed vacuoles were younger, suggesting that rimmed vacuoles may be a later feature of the disease.
  
  
  CONCLUSIONS
  These findings have important implications for diagnosis and future studies or trials in IBM as adherence to histopathologically focused diagnostic criteria will exclude large numbers of patients with IBM. Importantly, those excluded may be at an earlier stage of the disease and more amenable to treatment.
authors.affiliation: Nuffield Department of Clinical Neurosciences, Oxford University Hospitals, , Oxford, UK.
authors.forename: Stefen
authors.initials: S
authors.lastname: Brady
authors.forename: Waney
authors.initials: W
authors.lastname: Squier
authors.forename: David
authors.initials: D
authors.lastname: Hilton-Jones
mesh_terms: D000367:Age Factors; D000368:Aged; D001706:Biopsy; D057210:Delayed Diagnosis; D003937:Diagnosis, Differential; D049310:Distal Myopathies / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology*; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D008931:Mitochondria, Muscle / Q000473:pathology; D018482:Muscle, Skeletal / Q000473:pathology; D018979:Myositis, Inclusion Body / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology*; D009460:Neurologic Examination; D016896:Treatment Outcome
chemical_list: D007166:Immunosuppressive Agents
keywords: Incl Body Myositis; Muscle Disease