Systemic lupus erythematosus-myositis overlap syndrome: report of 6 cases

The incidence of myositis in patients with systemic lupus erythematosus (SLE) is low among different series. Here we attempt to describe the main features of SLE/myositis overlap syndrome. We retrospectively reviewed the medical records of 174 patients with SLE seen over 15-year period. All the patients fulfilled the revised American Rheumatology Association criteria for SLE. Patients who met The Bohan and Peter criteria for definite myositis were included in this study. Among those patients, six patients had an associated myositis (3.4% overall). They were 6 women with a mean age of 29 years (20-41 years). At the initial evaluation, 3 patients (50%) were complained from myalgia, and all patients had symmetrical muscle weakness (proximal muscle weakness in 6 cases with distal muscle weakness in 2 cases). The muscle disease was severe in 1 case. Involvements of muscles of the pharynx and upper esophagus were noted in 4 patients (66.6%). The creatine kinase (CK) levels were elevated in 4 cases with a mean rate of 2153.5 UI/L. The electromyogram (EMG) revealed signs of myositis in 5 cases. Muscle biopsy, performed in 5 patients, revealed an inflammatory myopathy changes in 4 cases. Antinuclear antibodies (ANA) were positive in all cases. All our patients were treated with high doses of corticosteroids with favorable outcome. Relapse of SLE disease had occurred in 2 patients. The association SLE-myositis is rare with heterogeneous presentation. Through our observations and literature data we will specify the characteristics of this association.