title: Polyarteritis nodosa presenting with clinical and radiologic features suggestive of polymyositis.
abstract: We report a patient who presented with clinical and MRI findings suggestive of polymyositis but, in whom, muscle biopsy disclosed a strikingly different diagnosis. A 65-year-old woman presented with 3-week history of bilateral proximal muscle pain and weakness. Laboratory investigations showed markedly elevated inflammatory markers and mildly elevated muscle enzymes. MRI scans of lower limbs showed features suggestive of polymyositis. However, muscle biopsy showed features of a polyarteritis-type vasculitis affecting an intramuscular blood vessel. Our reports highlight the critical role of muscle biopsy in establishing the correct diagnosis in patients with suspected myositis.
authors.affiliation: Department of Rheumatology, Cork University Hospital, Cork, Ireland. Mharoon301@hotmail.com
authors.forename: Muhammad
authors.initials: M
authors.lastname: Haroon
authors.forename: Niamh
authors.initials: N
authors.lastname: Bermingham
authors.forename: Catherine
authors.initials: C
authors.lastname: Keohane
authors.forename: Sinead
authors.initials: S
authors.lastname: Harney
mesh_terms: D000368:Aged; D001706:Biopsy; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D018482:Muscle, Skeletal / Q000473:pathology*; D010488:Polyarteritis Nodosa / Q000473:pathology*; D017285:Polymyositis / Q000473:pathology*