MUSCLE INVOLVEMENT IN RHEUMATOID-ARTHRITIS - CLINICOPATHOLOGICAL STUDY OF 21 SYMPTOMATIC CASES

The aim of the current study was to analyze the frequency and characte ristics of symptomatic myopathies occurring in rheumatoid arthritis (R A) patients, to correlate these findings with clinical data, and to ev aluate their therapeutic implications. All RA patients from a cohort o f 350 RA patients from a single institution who developed muscular sym ptomatology during an 8-year period were included in the study (n = 21 ). Clinical and laboratory data and electromyographic results were rec orded in all cases, and an open muscle biopsy was performed. Weakness and muscle atrophy were the most common symptoms. Serum creatine kinas e was increased in 8 cases (38%). Histopathologic study showed type 2 atrophy in 12 cases. In 13 cases, a treatable disease was diagnosed: d ermatomyositis (n = 2), d-penicillamine-related dermatomyositis (n = 2 ), polymyositis (n = 1), muscular mononuclear cell infiltration (n = 3 ), polyarteritis nodosa (n = 1), glucocorticoid myopathy (n = 3), and toxic chloroquine myopathy (n = 1). In all but 1 patient, muscular cli nical response to new therapy and/or drug withdrawal was satisfactory. Although symptomatic muscular involvement in RA is low (6% in the cur rent series), we have found that nearly two thirds of cases were cause d by potentially treatable conditions, mainly myositis or toxic myopat hies. Copyright (C) 1996 by W.B. Saunders Company