Pathological characteristics of skeletal muscle in patients with polymyalgia rheumatica / 中华老年医学杂志

ABSTRACT

Objective To study the pathological characteristics of skeletal muscle in patients with polymyalgia rheumatica(PMR).Methods Thirteen patients were diagnosed PMR according to the diagnostic criteria described by Bird in 1979.The onset of disease was between 49-78 years of age (median 60.3 years).All of them showed continuous symmetric myalgia with markedly elevated erythrocyte sedimentation rate(ESR).Five patients had mild fever and 8 patients had elevated C-reactive protein(CRP).Electromyogram(EMG)showed myogenic pattern in 2 patients.Only 1 patient showed anemia and 2 patients had mild elevated creatinine phosphokinase.None of them showed evidence of temporal arteritis.Biceps brachii muscle biopsies were performed in all patients before corticosteroid therapy.Results The typeⅡmuscle fiber atrophy was observed in all patients.Moth-eaten changes appeared in 8 cases,increased intramuscular lipid drops in 8 cases and ragged red fibers(RRF)in 3 cases of them.After steroid therapy,all patients showed improvement of myalgia and normal ESR as well as CRP.Conclusions The main symptoms of the patients are myalgia and abnormal ESR.Some patients have high level of CRP and abnormal EMG.Anemia and temporal arteritis are less frequent.The main myopathological changes were typeⅡmuscle fiber atrophy.Some patients have moth-eaten changes.More lipid drops and RRF indicate abnormal metabolism of skeletal muscle.