P.14.2 Dermatomyositis associated with MDA-5 antibodies: Report of the first European series

Phenotypic heterogeneity is very frequently observed in dermatomyositis (DM) patients depending on muscular weakness severity and extra-muscular involvement including interstitial lung disease or neoplasia. Dermatomyositis specific auto-antibodies are observed in 30% of patients. Among them an autoantibody recognizing melanoma differentiation-associated protein-5 (MDA-5) has been reported mainly in asiatic patients. We described here the first European study. We report the first French retrospective series of MDA-5 positive DM. MDA-5 antibodies were detected by Immunodot (D-Tek®). Seventeen patients (11 women, 10 Afro-Caribbean) have been included. The mean age was 44.2 [16–71] at presentation. Only two patients had severe muscle weakness and five had increase CK level. Muscle biopsy was always abnormal (n = 7) showing infiltrates (n = 6) and/or endomysial fibrosis (n = 1). One patient had severe myocardial impairment. Interstitial lung disease was often present (12/14) and subacute in 9 patients. CTscan demonstrated a pattern of non specific interstitial pneumonitis (n = 13), and/or organized pneumonia (n = 8). All patients had skin manifestations (n = 14): ulcerations or skin necrosis (n = 6), hyperkeratosis (n = 3), facial erythema (n = 4) and Raynaud’s phenomenon (n = 4). All patients suffered from arthralgia. Six patients had polyadenopathy. During follow-up (mean 44.2 months), 5 patients have been admitted in intensive care unit for an acute respiratory failure and 2 patients died, from respiratory cause (n = 1) and infection (n = 1). One patient had a cavum carcinoma. MDA-5 positive DM patients have a homogeneous presentation. Muscular disease is not severe whereas extra-muscular involvement is at the foreground lesions and may lead to life threatening complications.