Association of polymyositis with rheumatoid arthritis

Abstract

The association of polymyositis (PM) and rheumatoid arthritis (RA) is described in a 40-year-old female Mexican patient who was studied for a long period of time. The characteristic changes of PM that preceded the onset of RA for 7 years included proximal symmetrical muscle weakness, increased creatine kinase activity, and distinctive electromyography and muscle biopsy results. The occurrence of RA during the final 4 years of the 11-year period was characterized by long-lasting deforming and symmetric polyarthritis, high positive rheumatoid factor, subcutaneous nodules, and erosive joint changes. Through observation, myopathic changes other than those from PM were excluded. Joint changes other than from RA were also ruled out. A review of the literature revealed few specific reports of the coexistence of both diseases.

Antisynthetase syndrome associated with long-standing rheumatoid arthritis

“…About 3-20% of patients with PM/DM have overlapping characteristics of RA [11], and anti-Jo-1 antibody is reported to be positive about 20-30% of patients with PM/DM. Thus, a small percentage of patients who have PM/DM overlapping with RA also have anti-Jo-1 antibody.…”

Dermatomyositis in Patients with Rheumatoid Arthritis During Adalimumab Therapy

“…An association of polymyositis (PM)/DM with RA has long been well known 2 . RA can precede myositis, or it can develop after the diagnosis of PM/DM 3 .…”

Dr. Brunasso and Dr. Massone reply

“…The coincidence of myopathies and RA has been previously described in case series of patients -7 cases of DM and RA, 16 cases of polymyositis (PM) and RA, and 15 cases of unspecified DM or PM associated with RA. However, no uniform criteria or detailed case records could be found regarding these cases and only 4 detailed case reports with clear overlap between RA and DM were found 2,3 . It is important to consider that patients with DM may also have joint manifestations that can be misinterpreted as RA, even if these manifestations rarely proceed to joint deformity and destruction 2 .…”

“…Drug-induced myositis, usually associated with chronic use of corticosteroids and chloroquine in patients with RA, can be another pitfall that might lead to the incorrect diagnosis of overlapping RA and PM 1 . So it is important to emphasize that there is no clear and confirmed relation between RA and DM, even if there is a significant increase in frequency of autoimmune diseases (including RA) in first-degree relatives of patients with idiopathic inflammatory myopathies 2,3,4 . This association between many autoimmune diseases can be explained by the fact that many disorders share genes that together act as polygenic risk factors for autoimmunity 4 .…”

“…First, the association between rheumatoid arthritis (RA) and dermatomyositis (DM) in a single patient seems to be infrequent and the real incidence is unknown 2,3 . The coincidence of myopathies and RA has been previously described in case series of patients -7 cases of DM and RA, 16 cases of polymyositis (PM) and RA, and 15 cases of unspecified DM or PM associated with RA.…”