Skin Biopsy May Be Required to Improve Diagnosis of Amyopathic Dermatomyositis

The European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria for idiopathic inflammatory myopathy (IIM) may be inadequate for diagnosing patients with amyopathic dermatomyositis (ADM), overlooking approximately one-fourth of individuals with the disease, according to the results of a recent retrospective study published in the Journal of the American Academy of Dermatology.

The investigators sought to evaluate the likelihood that the 3 skin variables included in the EULAR/ACR criteria (Gottron’s sign, Gottron’s papules, and heliotrope rash) would yield a high probability of classifying patients with ADM. A total of 211 individuals with DM were included in the analysis.

Mean patient age was 51.9±13.3 years; the majority of patients were women (84.8%) and Caucasian (89.1%). Of those enrolled, 47.9% (101 of 211) had classic DM and 52.1% (110 of 211) had clinically ADM.

All patients’ DM skin disease activity was assessed using the Cutaneous Dermatomyositis Disease Area and Severity Index and was scored from 0 to 100 based on the presence of erythema, scale, erosion, and ulceration.

Results of the study demonstrated that overall, 73.7% (73 of 99) of patients with ADM would be classified as having a reasonable probability (>55%) of idiopathic inflammatory myopathy, according to current EULAR/ACR criteria. Moreover, 26.3% (26 of 99) of those with ADM would not meet the suggested 55% minimum cutoff (10% to 55% probability in 20 [20.2%] of 26 patients and <10% probability in 6 [6.1%] of 26 patients) for being classified as having idiopathic inflammatory myopathy.

The researchers concluded that the consideration of additional variables, such as skin biopsy, should be used in these analyses to involve more patients and prevent the inclusion of any cutaneous diseases that mimic ADM.

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Patel B, Khan N, Werth VP. Applicability of EULAR/ACR classification criteria for dermatomyositis to amyopathic disease [published online December 29, 2017]. J Am Acad Dermatol. doi: 10.1016/j.jaad.2017.12.055