What is the treatment for dermatomyositis?

Treatment of Dermatomyositis

Begin treatment immediately at diagnosis with high-dose oral corticosteroids (prednisolone 1-2 mg/kg/day, maximum 60-80 mg/day) combined with methotrexate 15-20 mg/m² weekly administered subcutaneously. 1, 2

Initial Treatment Regimen

The cornerstone of dermatomyositis management involves dual immunosuppressive therapy from the outset:

• Start oral prednisolone at 1-2 mg/kg/day (maximum 60-80 mg/day) combined with methotrexate 15-20 mg/m² weekly 1, 2
• Administer methotrexate subcutaneously rather than orally for superior absorption 1, 2
• For severe presentations with profound weakness or major organ involvement, use high-dose intravenous methylprednisolone before transitioning to oral therapy 2
• Prednisone is FDA-approved for systemic dermatomyositis (polymyositis) 3

Essential Adjunctive Measures

These non-pharmacologic interventions must be implemented immediately:

• Provide rigorous sun protection to prevent photosensitive rash exacerbations 1, 2
• Prescribe calcium and vitamin D supplementation to prevent corticosteroid-induced osteoporosis 1, 2
• Initiate a supervised physiotherapy program to restore muscle strength during remission 1, 2

Treatment Algorithm Based on Response

At 2-4 Weeks:

• If clinical improvement occurs, begin tapering corticosteroids while maintaining methotrexate 1, 2
• Continue monitoring muscle strength using validated measures (Manual Muscle Test, Childhood Myositis Assessment Scale) 1

At 12 Weeks:

• If no improvement, verify medication adherence and tolerance before escalating therapy 1, 2
• Check for methotrexate intolerance or inadequate dosing 1

Management of Inadequate Response or Intolerance

For Methotrexate Intolerance:

• Switch to mycophenolate mofetil or cyclosporine A as alternative DMARDs 1, 2

For Inadequate Response Despite Adherence:

• Add intravenous immunoglobulin (IVIG), which shows particular efficacy for cutaneous manifestations 1, 2
• Consider cyclophosphamide 500-1000 mg/m² IV monthly for severe disease with major organ involvement or extensive ulcerative skin disease 1
• Alternative intensification options include high-dose methotrexate or cyclosporine A 1

Management of Refractory Disease

For patients failing standard therapy:

• Consider rituximab for refractory cases, but counsel patients that clinical response may take up to 26 weeks 1, 2
• Anti-TNF therapies (infliximab or adalimumab preferred over etanercept) may be considered 1
• Avoid TNF-α antagonists as they can exacerbate interstitial lung disease and myositis and increase infection risk 4

Persistent Skin Disease Management

Ongoing cutaneous manifestations require specific attention:

• Persistent skin disease reflects ongoing systemic inflammation and requires increased systemic immunosuppression 1
• Apply topical tacrolimus or topical corticosteroids for localized symptomatic redness or itching 1
• Intensify immunosuppressive therapy for calcinosis (calcium deposits in the skin) 1
• Monitor cutaneous disease activity using a cutaneous assessment tool including nailfold capillaroscopy 1

Treatment Duration and Withdrawal

• Gradually wean corticosteroids as clinical improvement occurs while continuing methotrexate 1, 2
• Treatment may be withdrawn if the patient has been off steroids and in remission on methotrexate for a minimum of 1 year 1
• Typical maintenance therapy duration is one to three years 5

Critical Monitoring Requirements

Regular assessment must include:

• Muscle strength evaluation using validated measures 1
• Assessment for major organ involvement, particularly interstitial lung disease (occurs in ~30% of patients) requiring pulmonary function tests 5
• Cardiac evaluation with troponin to assess for myocardial involvement 6
• Laboratory monitoring: CK, transaminases (AST, ALT), LDH, aldolase, ESR, CRP 6, 1

Special Considerations

Malignancy Screening:

• Approximately 5-20% of adult dermatomyositis cases are associated with malignancy 5
• Perform age-appropriate cancer screening, but do not delay treatment of severe myositis 5

Juvenile Dermatomyositis:

• Use corticosteroids 2 mg/kg/day up to maximum 60 mg/day with subcutaneous methotrexate 15 mg/m² weekly 2
• Monitor vigilantly for calcinosis cutis, cutaneous vasculitis, and gastrointestinal vasculopathy 2

Common Pitfalls to Avoid

• Do not use oral methotrexate when subcutaneous administration is feasible due to inferior absorption 1, 2
• Do not delay adding methotrexate to corticosteroids—dual therapy from the outset improves outcomes 1, 2
• Do not continue ineffective therapy beyond 12 weeks without reassessing diagnosis—consider repeat muscle biopsy to exclude other myopathies 4
• Do not use etanercept if anti-TNF therapy is considered—infliximab or adalimumab are preferred 1