Amyopathic dermatomyositis or dermatomyositis-like skin disease: retrospective review of 16 cases with amyopathic dermatomyositis

Amyopathic dermatomyositis (ADM) is characterized by the presence of dermatomyositis (DM) for 6 months or more in individuals who have normal muscle enzymes and no clinically significant muscle weakness. The aim of the study was to investigate the initial laboratory data, clinical manifestations, complications, and clinical outcomes of patients with the diagnosis of ADM. We reported 16 cases with the cutaneous findings of dermatomyositis without clinical or laboratory evidence of muscle disease for at least 2 years after onset of the skin manifestations in the Department of Dermatology and Rheumatology at Shanghai Ruijin Hospital between 1998 and 2004. All patients had Gottron's papules, periungual erythema/telangiectasia, and violaceous discoloration of the face, neck, upper chest, and back at some time during the course of their disease. Follow-up of 1 to 10 years after diagnosis found muscle weakness in three patients (18.75%) within 5 years of diagnosis. One patient (6.15%) was rediagnosed as chronic cutaneous lupus erythematosus (CCLE). Four patients (25%) had associated malignancies. Twelve patients (75%) had radiographic evidence indicative of interstitial fibrosis irrespective of respiratory symptoms. Patients with ADM appear to be at risk for developing the same potentially fatal disease complications as those patients with DM (e.g., interstitial lung disease and internal malignancy). These cases further emphasize that the cutaneous manifestations of dermatomyositis are pathognomonic for DM and we propose the term dermatomyositis-like skin disease as a better designation than amyopathic dermatomyositis to describe this distinctive subset of cutaneous symptoms. Dermatomyositis-like skin disease is a complex syndrome, which includes the characteristic cutaneous eruption of dermatomyositis without clinical evidence of muscle disease. Our findings suggest that patients diagnosed with this syndrome are at risk for fatal interstitial lung disease, malignancy, and/or delayed onset of DM or CCLE. Cautious systematic clinical trials should be considered for this group of patients.