There is an increased incidence of malignancy in patients with dermatomyositis. It is unknown if the risk differs between the subtypes of dermatomyositis.
(1) Compare the prevalence of malignancy-associated dermatomyositis between patients with classic and clinically amyopathic disease. (2) Determine factors associated with an increased risk of malignancy-associated disease.
Retrospective cohort study of 201 patients with adult-onset dermatomyositis prospectively enrolled in a longitudinal dermatomyositis database between July 2008 and April 2018 at an outpatient dermatology urban tertiary referral center. The main outcome measure was a diagnosis of malignancy, excluding non-melanoma skin cancer.
There were 201 patients with adult-onset dermatomyositis: 142 (71%) classic and 59 (29%) clinically amyopathic. Within 2 years of diagnosis, the prevalence of malignancy-associated classic and clinically amyopathic dermatomyositis was 9.9% and 1.7%, respectively. In this time period, patients who were older at dermatomyositis diagnosis (p = 0.01) and had the classic subtype (p = 0.04) were significantly more likely to have an underlying malignancy on multivariable regression analysis.
This was a retrospective study of prospectively collected data at a single tertiary referral center.
Older age and classic dermatomyositis are independent risk factors for malignancy-associated dermatomyositis within 2 years of disease onset.

Copyright © 2020. Published by Elsevier Inc.