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HISTORY
Dermatomyositis has been recognized as a clinical entity for more than 100 years. Although the first adult patients with dermatomyositis and malignancy were described early in the twentieth century, a causal association was not suggested until the 1940s. A major step forward in the understanding of this disorder occurred in 1975, when Bohan and Peter proposed generally accepted clinical diagnostic criteria. Over the past two decades, it has become more widely accepted that a subset of patients has skin-limited disease (i.e. amyopathic dermatomyositis). For this reason, Sontheimer proposed a revised classification of the idiopathic inflammatory myopathies that includes amyopathic forms of dermatomyositis, with muscle involvement no longer required for a definitive diagnosis (Table 42.1). Based upon epidemiologic studies, an estimated 20% of dermatomyositis patients have clinically amyopathic disease.
Table 42.1 Revised classification system for the idiopathic inflammatory dermatomyopathies. This classification scheme recognizes, with equal weighting, the cutaneous and muscle manifestations of this group of disorders. Adapted from Sontheimer RD. Would a new name hasten the acceptance of amyopathic dermatomyositis (dermatomyositis sine myositis) as a distinctive subset within the idiopathic inflammatory dermatomyopathies spectrum of clinical illness? J Am Acad Dermatol 2002;46:626โ36.