[Dermatomyositis-update].

Dermatomyositis is a rare idiopathic inflammatory myopathy that affects adults and children, mostly female. Hallmarks of the disease are myositis with necrosis, regeneration and perifascicular atrophy accompanied by a typical skin rash with heliotrope erythema, Gottron's sign, Gottron's papules and nail fold changes with splinter hemorrhage. Typical skin symptoms may appear 6 months up to 2 years before muscle involvement (amyopathic dermatomyositis). New myositis-specific antibodies may allow clinicoserologic correlations within a heterogeneous clinical spectrum. Autoantibody profiles, subtype of myositis, overlap with other collagen vascular disorders and/or malignancy (paraneoplastic dermatomyositis) as well as age of the patients all have a considerable impact on course and prognosis. Infections, drugs and tumors may trigger activation of T and B cells, plasmacytoid dendritic cells, overproduction of type I interferons and complement-mediated endothelial cell damage resulting in vasculopathy. UV radiation may also trigger dermatomyositis. Oral corticosteroids (1.5-2.0 mg/kg body weight/day) are the mainstay of treatment until improvement of muscle symptoms and/or normalization of muscle enzymes with subsequent slow tapering. Corticosteroids may be given as monotherapy or combined with steroid-sparing immunosuppressive agents' i.e. azathioprine, methotrexate, mycophenolate mofetil or high-dose intravenous immunoglobulins. Prognosis has improved considerably since use of high-dose corticosteroids, from 50 to 90% response rate. New therapies with biologicals (anti-CD20-, anti-TNFalpha-, anti-interferon antibodies) and Janus kinase inhibitors are currently being evaluated.