Amyopathic dermatomyositis: definitions, diagnosis, and management.

Amyopathic dermatomyositis can be a challenging diagnosis because patients lack traditional muscle findings. "Clinically amyopathic" dermatomyositis (CADM) accounts for the presence of subclinical muscle disease in some of these patients. These patients represent a substantial minority of dermatomyositis cases and have similar co-morbidities to "classic" dermatomyositis patients, including interstitial lung disease and malignancy. Clinically amyopathic dermatomyositis patients should not be considered as a distinct clinical entity from "classic" dermatomyositis, as they share antibody sub-types and associated co-morbidities, likely representing clinical spectrum of a common disease. It is essential for the clinician to be familiar with the clinical presentation of clinically amyopathic dermatomyositis, in order to facilitate early, accurate diagnosis and appropriate clinical management.