Idiopathic inflammatory myopathies with anti-PM-Scl antibodies: case series and literature review

The objectives of this study were to evaluate: (1) the prevalence of anti-PM-Scl antibodies within the framework of antinuclear antibodies detection; and (2) the clinical features and outcome of patients with isolated polymyositis/dermatomyositis. Nine thousand and sixty-four consecutive antinuclear testing data allowed us to evaluate anti-PM-Scl antibody prevalence. Second, we also assessed the characteristics of patients with isolated dermatomyositis/polymyositis and associated anti-PM-Scl antibody. Over 9064 consecutive antinuclear samples tested for antinuclear antibodies, 3263 (36%) were positive; anti-PM-Scl antibody were positive in nine patients: 0.1% of all sera, 0.2% of sera positive for antinuclear antibodies, 1.2% of sera positive for anti-ENA antibodies. Four of the nine patients with anti-PM-Scl antibody had dermatomyositis (n=3) and polymyositis (n=1). Patients with dermatomyositis/polymyositis and anti-PM-Scl antibody exhibited severe complications, as follows: ventilatory insufficiency (n=2) requiring mechanical ventilation in one case, esophageal involvement requiring enteral feeding (n=1); also, two of these patients had cancer. Our case series suggests that the presence of anti-PM-Scl antibody is not a favorable prognostic factor in patients with dermatomyositis/polymyositis. This type of antibody appears to be associated with lung and esophageal involvement; in addition, anti-PM-Scl antibody may co-exist with malignancy in PM/DM patients. Taken together, we suggest that patients with dermatomyositis/polymyositis and anti-PM-Scl antibody require both initial evaluation for lung/digestive manifestations and cancer and close surveillance.