ARTICULAR MANIFESTATIONS OF POLYMYOSITIS WITH ANTI-SYNTHETASE SYNDROME

Background: Arthritic features have been described in 35 p. cent of patients diagnosed as having polymyositis. A subluxing non erosive arthropathy with apatite deposition is a particular feature of patients with anti-synthetase (i.e JO1, PL7) antibodiesObjectives: To describe the different rheumatic features of patients with polymyositis and/or anti-synthetase syndromeMethods: Between 9/2005 and 11/2006 rheumatologist and internal medicine practitioners from all medical centres registered on the web site of the CRI (Club Rhumatismes et Inflammation) were e.mailed to obtain the demographic and clinico-biological characteristics of patients with anti-synthetase syndrome in order to describe rheumatic features using a standardized online questionnaire. Patients without articular manifestation were excluded.Results: 39 cases (30 F/9H; 33 Caucasians, 6 Blacks) were collected and analysed. Patients were classified in 3 groups according to the dominant articular features: 5 with non erosive deforming arthropathy (DA group), 24 with a non deforming polyarthritis (P group) and 10 with arthromyalgias (A group). Most patients had polymyositis and/or anti-synthetase syndrome (n=32), dermatomyositis was present only in P group (n=4) and A group (n=3). Overlap features were present in 12 patients such as Sjögren syndrome (n=7), RA (n=4), PSS (n=1) or SLE (n=1), more frequently in P group (42% vs 20% in both other groups). The mean age at time of the first articular feature was identical among the 3 groups, however the time elapsed between the first articular symptom and the diagnosis of anti-synthetase syndrome was ten times higher in the DA group (10,4±10,2 years) than in the other groups: 0,8±2,3 y or 0,7±0,1 y (p<0,0001). The 10 patients with pure arthralgias (A group) had objective myositis (Bohan and Peter criteria). Myositis was not a constant feature in the other groups at the time of anti-synthetase syndrome: 60 to 74 p. cent. A bilateral "floppy thumb" was the most characteristic manifestation of the deforming subluxing arthropathy (DA) group. The most affected arthritic sites were the wrists, MCP, DIP and PIP of both hands. Knees, heels, elbows and shoulders were concerned mainly in patients from the polyarthritis group (P group). Other relevant rheumatic features were: tenosynovitis, carpal tunnel syndrome, Raynaud's phenomenon, mechanics hand and periarticular calcinosis. This feature was more frequent in the DA group (p<0,05). Rheumatoid factor and anti-CCP antibodies were seen in patients from the P group (29% and 10%). Four patients from the P group had erosions on radiographs (overlap with RA). Antinuclear antibodies were detected in patients from P (58%) and A groups (70%) and anti-SSA (Ro) antibodies were significantly more frequent (p<0,02) in the DA group (80% vs 42% and 19%). Anti-J01 was detected in 33 patients, anti-PL7 in 3 and other specificities in 3.Conclusion: These data suggest that deforming subluxing distal arthropathy is a characteristic feature of patients with anti-synthetase syndrome and may antedate by many years the other extra-articular (alveolitis, myositis) characteristics of the syndrome. Non deforming polyarthritis is the more frequent clinical presentation: erosions are associated with an RA overlap syndrome.Citation: Ann Rheum Dis, volume 66, supplement II, year 2007, page 249Session: Miscellaneous rheumatic diseases