Dermatomyositis

An idiopathic inflammatory myopathy characterized by the presence of hallmark cutaneous lesions (e.g., heliotrope rash, Gottron papules).

Skin lesions are frequently the initial presenting complaint, with muscle involvement developing later.

Some patients have cutaneous involvement alone.

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

Initial treatment of muscle disease is with high-dose oral corticosteroids (prednisone), followed by the addition of immunosuppressants and intravenous immunoglobulin in refractory cases.

Skin manifestations are treated with topical antipruritics and topical corticosteroids. Antimalarials, topical tacrolimus, immunosuppressants, and intravenous immunoglobulin are generally used for resistant or severe skin disease. Photoprotection is advised in all patients.

Dermatomyositis (DM) is an idiopathic inflammatory myopathy characterized by 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 (scleroderma, systemic lupus erythematosus, mixed connective tissue disease, and, less often, rheumatoid arthritis and Sjogren 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 It may be associated with interstitial lung disease, cardiac involvement, esophageal involvement, and underlying malignancy. Adult-onset DM is significantly associated with occult malignancy.[4]Sigurgeirsson B, Lindelof B, Edhag O, et al. Risk of cancer in patients with dermatomyositis or polymyositis: a population-based study. N Engl J Med. 1992 Feb 6;326(6):363-7. http://www.ncbi.nlm.nih.gov/pubmed/1729618?tool=bestpractice.com