Joint involvement in polymyositis/dermatomyositis.

The frequency and features of joint involvement were evaluated in 29 patients with polymyositis/dermatomyositis (PM/DM); eight of them (27.5%) presented arthritis. Mean age was 30 years, and mean disease duration was 5.3 years. Oligoarthritis was observed in 5 cases, while 3 presented polyarthritis; in most cases arthritis was concurrent with the musculocutaneous picture. On comparing the 8 arthritis patients with the remaining 21, no significant clinical or serological differences were found. However, males predominated in the arthritis group, 75% vs 19% (p < 0.05). Arthritis responded favourably to underlying disease treatment and articular sequelae were not observed.