Dermatomyositis

Dermatomyositis (DM) is an idiopathic autoimmune inflammatory disorder characterised 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's papules, photosensitivity, and nail fold capillary dilatation.

May be associated with interstitial lung disease, cardiac involvement, oesophageal 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 immunoglobulin 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 intravenous immunoglobulin are generally used for resistant and severe skin disease. Photoprotection is advised in all patients.

Dermatomyositis (DM) is an idiopathic autoimmune inflammatory myopathy characterised by distinctive skin manifestations. Diagnosis is based on the presence of a symmetrical proximal myopathy, raised 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's 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's 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, oesophageal involvement, dystrophic calcification, 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