Background/Purpose: Clinically amyopathic dermatomyositis (CADM) is an important subset and accounts for approximately 20% of patients with dermatomyositis (DM). CADM is characterized by the presence of pathognomonic cutaneous findings without symptoms of muscle weakness. Cutaneous DM can be difficult to treat and is often refractory to photoprotection and topical therapy, frequently requiring additional systemic treatment even in the absence of muscle involvement. In our series, we investigate the use of systemic medications for treating CADM in our tertiary care center.

Methods:  Retrospective chart review was conducted using the Partners Healthcare Research Patient Data Registry, which includes over 1.8 million outpatient visits in a university setting. Patients with CADM (including amyopathic and hypomyopathic DM) diagnosed and treated by any dermatology provider between January 2010 and January 2014 were identified. Data collected included demographics, referral type, diagnosis, medications used for DM, medication side effects, and laboratory tests including anti-nuclear antibody (ANA) and anti-Jo-1 (Jo-1).

Results: We identified 36 patients with CADM (6 hypomyopathic and 30 amyopathic).  47% of patients were referred from dermatology providers, 38.8% from rheumatology , 8.3% from primary care, and 5.5% were self-referred. Only one male patient was identified. One patient was Asian, the remainder Caucasian.  Mean age of diagnosis was 50 years (±17.1, range 21-86). 41% of patients were diagnosed within 6 months from the onset of their rash. 36.1% were treated with hydroxychloroquine and topical corticosteroids alone, while 63.9% required at least one additional immunosuppressive therapy. Medications used for control of cutaneous disease included, methotrexate (47.2%), IVIG (30.6%), prednisone (30.5%), mycophenolate mofetil (16.7%), azathioprine (5.6%), rituximab (8.3%), and others including but not limited to dapsone and thalidomide (13.9%). Notably, 25% of patients developed a cutaneous hypersensitivity reaction to hydroxychloroquine. Of the 31 patients with laboratory data available, most (64.5%) had a positive ANA, while no patient had a detectable Jo-1 antibody.

Conclusion: Our series demonstrates that photoprotection, topical therapy, and hydroxychloroquine control disease in only a third of patients with CADM, thus underscoring the frequently refractory nature of skin disease and the need to treat with additional systemic therapy. Methotrexate and IVIG were the most commonly used additional therapies to treat CADM. Furthermore, the risk of cutaneous hypersensitivity reaction to hydroxychloroquine in this series of patients with CADM was similar to that reported in the literature for patients with DM.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/systemic-treatment-for-clinically-amyopathic-dermatomyositis/