Background/Purpose: Dermatomyositis (DM) is a multisystem autoimmune disease that affects the muscles and skin and can be associated with malignancy or interstitial lung disease (ILD).  Cutaneous ulceration can be seen in patients with dermatomyositis, and this has classically been associated with internal malignancy.  We have recently described that ulceration can also be associated with antibodies against melanoma differentiation-associated gene 5 (MDA5), a DM-specific autoantigen that is associated with ILD, and mild or no muscle disease.  We sought to better describe cutaneous ulceration in DM and to specifically identify clinical and serologic correlates of ulcers and their anatomic location.

Methods: We retrospectively examined a cohort of 131 DM patients followed in our interdisciplinary rheumatology-dermatology clinic. We collected data on demographics, ANA and DM-associated auto-antibodies (Jo-1, NXP2, Mi2, TIF-Gamma, SAE1, Ro52, MDA5) and clinical features including presence and location of ulcers, ILD (evidence of fibrosis or alveolitis on computed tomography), and malignancy within 3 years of symptom onset. The cutaneous ulcer locations were subdivided into three categories: ulcerations over joints (Gottron papules, knees, or elbows); ulcerations of the digital pulp or periungual region; and ulcers elsewhere on the body including those in sun-exposed areas. We compared the features of patients with ulcers to those without ulcers using chi-squared tests.  We used univariate and multivariate logistic regression models to identify significant predictors for the presence of ulcers and ILD.

Results: In the overall cohort, the mean age was 45±19 years, 31% were male, and the ethnic distribution was 66% Caucasian, 19% Asian, 5% African American, and 10% Hispanic.  40 patients had cutaneous ulcers and 91 patients did not have ulcers. 50% of patients had ulcers over the Gottron papules and extensor surfaces, 40% at the digital pulp or periungual areas, and 62.5% had ulcers located elsewhere. Patients with any cutaneous ulcers were more likely to be Asian (p=.006) or anti-MDA5+ (p<.0001).  We did not find a significant association between ulcers and malignancy.  In multivariate analysis MDA5+ remained significant and increased the odds of ulcers by 10-fold (OR=10.1, 95%CI 2.0-51.8, p=.006).  Examining only the ulcer+ patients, ulcers located at the digital pulp or periungual areas was associated with a 20-fold increased odds of being MDA5+ (OR= 20.9, 95%CI 3.5-126.5, p=.0009). Consistent with previous reports, MDA5+ was associated with an increased risk for ILD (OR=5.8, 95%CI 1.8-18.4, p=.003), that was higher in the presence of ulcers (OR=8.3, 95%CI 2.5-28.3, p=.0007), particularly if located at the digital pulp or periungual areas (OR=14.2, 95%CI 3.4-58.3, p=.0002).

Conclusion: We confirmed the strong association between MDA5+ and cutaneous ulcers, with the novel finding that ulcers located at the digital pulp and periungual areas are highly predictive of the presence of ILD in these patients.  DM patients who display this cutaneous phenotype should undergo appropriate evaluation for ILD.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/cutaneous-ulceration-in-dermatomyositis-association-with-mda-5-and-interstitial-lung-disease/