[Update: dermatomyositis].

Dermatomyositis is an idiopathic inflammatory myopathy and an "orphan disease" (incidence 1:100,000). It comprises a heterogenous clinical spectrum with periorbital heliotrope erythema, acral Gottron papules, and proximal muscle weakness. Muscle-specific antibody profiles correlate with clinical variants. Overlap with other collagen vascular disorders occurs and about one-third of patients have an underlying malignancy (paraneoplastic dermatomyositis). High-dose oral corticosteroids are the mainstay of treatment, given until improvement of muscle symptoms and/or normalization of muscle enzymes Additional options include steroid-sparing immunosuppressants, or high dose intravenous immunoglobulins. Prognosis has improved considerably since use of high-dose corticosteroids, with about 90% of patients responding. Follow-up and search for a possible malignancy should be performed yearly.