Dermatomyositis

Dermatomyositis (DM) is an idiopathic autoimmune inflammatory disorder characterized by a myopathy with a distinctive cutaneous eruption.

Skin lesions are frequently the initial presenting complaint, with muscle involvement developing later. Some patients have cutaneous involvement alone. Hallmark features include a heliotrope rash, Gottron papules, photosensitivity, and nail fold capillary dilatation.

May be associated with interstitial lung disease, cardiac involvement, esophageal involvement, dystrophic calcification, and underlying malignancy.

Initial treatment of muscle disease is with high-dose oral corticosteroids, followed by the addition of immunosuppressants or intravenous immune globulin (IVIG) in refractory cases.

Skin manifestations are treated with topical antipruritics and topical corticosteroids. Antimalarials and topical tacrolimus can be used in resistant disease.

Immunosuppressants and IVIG are generally used for resistant and severe skin disease. Other treatments for refractory disease include biologic agents and Janus kinase (JAK) inhibitors.

Photoprotection is advised in all patients.

DM is an idiopathic autoimmune inflammatory myopathy characterized by distinctive skin manifestations. Diagnosis is based on the presence of a symmetric proximal myopathy, elevated muscle enzymes, myopathic changes on electromyography, a characteristic muscle biopsy, and a typical skin rash (e.g., periorbital dusky violaceous erythema, or macular violaceous erythema such as in V, shawl, and Gottron signs).[1]Bohan A, Peter JB. Polymyositis and dermatomyositis (second of two parts). N Engl J Med. 1975 Feb 20;292(8):403-7. http://www.ncbi.nlm.nih.gov/pubmed/1089199?tool=bestpractice.com Some patients present with typical cutaneous manifestations but have delayed-onset, subclinical, or absent muscle disease.[2]Gerami P, Schope JM, McDonald L, et al. A systematic review of adult-onset clinically amyopathic dermatomyositis (dermatomyositis sine myositis): a missing link within the spectrum of idiopathic inflammatory myopathies. J Am Acad Dermatol. 2006 Apr;54(4):597-613. http://www.ncbi.nlm.nih.gov/pubmed/16546580?tool=bestpractice.com DM occurs in both adult and juvenile forms and can overlap with other connective tissue disorders (systemic sclerosis, systemic lupus erythematosus, mixed connective tissue disease, and, less often, rheumatoid arthritis and Sjögren syndrome).[3]Dalakas MC, Hohlfeld R. Polymyositis and dermatomyositis. Lancet. 2003 Sep 20;362(9388):971-82. http://www.ncbi.nlm.nih.gov/pubmed/14511932?tool=bestpractice.com However, we only include recommendations for the diagnosis and treatment of adult-onset DM in this topic.