The chameleon rash: a review of the polyphenotypic dermatoses of dermatomyositis.

Dermatomyositis (DM) is an autoimmune connective tissue disease which is included in the idiopathic inflammatory myopathies. Cutaneous manifestations are a prominent part of the condition: some skin signs in DM are common to most patients, other signs are encountered infrequently. A number of features are pathognomic for DM. The demonstration of myositis specific antibodies (MSA) in DM has extended our ability to define phenotypic subgroups. It appears that the presence of certain MSAs confers susceptibility to specific clinical features, an association which reveals a serotype-phenotype relationship. In this review article we have provided a detailed summary of common and under-recognised cutaneous manifestations of DM.