Myositis as a rare complication after tocilizumab treatment

Methods A 6-year-old boy affected by an overlap autoimmune syndrome characterized by facial skin lesions chilblain lupus like (histopathologically compatible with leukocytoclastic vasculitis), recurrent skin urticarial episodes and a severe lung disease (in the anatomopathological study is a linfoid intersticial neumonitis). He presents antinuclear antibodies positivity (maximum title reported 1/640), an undetermined antiDNA antibodies title (values around 31 UI/ml), no complement consumption of C3 neither C4, positives antiB2-glycoprotein and anticardiolipin IgG antibodies with persisting elevation of acute phase reactants highlighting an ESR permanently around 100 mm/h and thrombocytosis around 500x10^9 platelets. An extended auto-antibodies study was repeatedly performed without finding other auto-antibodies positivity. Several therapeutic strategies with different agents were previously tested (corticoids, azathioprine, hydroxychloroquine, anakinra, mycophenolate, gammaglobulin, tacrolimus). All of these therapies were discontinued because of inefficacy or lack of efficacy, and resolution of symptoms wasn’t achieved.