5th June 2025

Management

Treatment depends on the presentation of dermatomyositis – though there can be some overlap in management, muscle and skin manifestations are treated with different agents. Dermatomyositis is considered to be the most responsive idiopathic inflammatory myopathy, but even with good control of myopathy, skin lesions may remain treatment-resistant. 

In severe disease or an acute flare, intravenous corticosteroids are used in the short-term until better control is achieved and the patient can be switched to oral agents. Patients with anti-synthetase syndrome may be corticoid-resistant and may require concomitant immunosuppressives. If anti-SRP positive, patients often require immunosuppressives, IVIG or rituximab early in the disease due to the association with acute severe recalcitrant necrotising myositis. If the patient is MDA5 positive, which is associated with rapidly progressive ILD, they often also require high-dose systemic corticosteroids from an early stage.

Management of myopathy

• First-line: high doses of oral corticosteroids
• Second-line: 
  • Methotrexate – often preferred over azathioprine as it acts quicker; a low dose is useful for both muscle and skin involvement; effective corticosteroid-sparing agent
  • Azathioprine – appears to take longer to have an effect (6 months or more)
• Third-line – can be used as a  monotherapy or combined with corticosteroids or other immunosuppressants
  • Ciclosporin – corticosteroid-sparing agent in some patients
  • Tacrolimus and mycophenolate 
  • Cyclophosphamide – useful in refractory disease associated with vasculitis, ILD or respiratory muscle involvement
  • Chlorambucil – successful in a few studies of refractory disease
• In some cases, the disease remains active regardless of any immunosuppressive therapy; Adjunctive IVIG in patients with significant muscle weakness has demonstrated some benefit in small studies and case reports

Management of skin manifestations

• First-line: topical therapy
  • Patient education regarding adequate sun protection due to photosensitive nature of skin lesions
  • Topical corticosteroids – beneficial even in patient who are already on systemic corticosteroids; help control erythema and pruritus 
  • Topical antipruritic treatments as adjuncts to topical corticosteroids – emollients with added menthol, phenol or camphor or topical antihistamines (e.g., Doxepin)
  • If severe pruritus unresponsive, trial of oral antihistamine
• Second-line: antimalarials 
  • Hydroxychloroquine – only effective for skin lesions and scalp pruritus with no effect on muscle symptoms
  • Chloroquine – risk of retinopathy greater than with hydroxychloroquine 
  • Topical tacrolimus – only anecdotal evidence exists for this agent
• Third-line: immunosuppressives
  • Methotrexate – can be used in combination with topical treatment and antimalarials; useful for both muscle and skin manifestations
  • Azathioprine – only anecdotal evidence exists of benefit in methotrexate-resistant dermatomyositis
  • Mycophenolate – shown to be beneficial in recalcitrant skin disease
  • Ciclosporin – beneficial in resistant skin disease and early ILD; contra-indicated in renal impairment and hypertension
  • Anti-inflammatory agents such as thalidomide and dapsone are alternatives to immunosuppressives – case reports and anecdotal evidence exist 
• Adjunctive IVIG can be used in refractory skin involvement.