What is the treatment for dermatomyositis?

Treatment of Dermatomyositis

The recommended first-line treatment for dermatomyositis is high-dose corticosteroids (preferably methylprednisolone pulse 15-30 mg/kg/dose for 3 consecutive days), followed by oral prednisolone 1-2 mg/kg/day, combined with methotrexate 15-20 mg/m² weekly, preferably administered subcutaneously. 1

Initial Treatment Approach

• Start high-dose corticosteroids at diagnosis or during disease flare 1
• Add methotrexate (MTX) 15-20 mg/m²/week (maximum absolute dose of 40 mg/week) concurrently with corticosteroids 1
• Administer MTX preferably subcutaneously for better absorption 1
• Provide sun protection and ensure adequate calcium and vitamin D intake to prevent complications 1
• Include a safe and appropriate exercise program monitored by a physiotherapist 1

Treatment Algorithm Based on Disease Severity

For Mild to Moderate Disease:

• Begin with high-dose corticosteroids and MTX as described above 1
• Regularly assess muscle strength, skin disease, and major organ involvement 1
• If improvement occurs, gradually wean steroids while continuing MTX 1
• If no improvement within 12 weeks, check adherence and medication tolerance 1

For Severe Disease (major organ involvement/extensive ulcerative skin disease):

• Consider adding cyclophosphamide 500-1000 mg/m² IV monthly 1
• Alternative intensification options include high-dose MTX, cyclosporine A, and IVIG 1
• Monitor closely for improvement in muscle strength and skin manifestations 1

Management of Refractory Disease

• For MTX intolerance, switch to another DMARD such as mycophenolate mofetil (MMF) or cyclosporin A 1
• For inadequate response, intensify treatment by adding IVIG, which has shown efficacy particularly for skin manifestations 1, 2
• Consider biologics for refractory cases: rituximab can be effective but may take up to 26 weeks to work 1
• Anti-TNF therapies (infliximab or adalimumab) may be considered, with infliximab or adalimumab preferred over etanercept 1
• Avoid TNF-α antagonists in patients with interstitial lung disease as they may exacerbate this condition 3

Ongoing Skin Disease Management

• Persistent skin disease reflects ongoing systemic inflammation and requires increased systemic immunosuppression 1
• Topical tacrolimus (0.1%) or topical steroids may help with localized skin disease, particularly for symptomatic redness or itching 1
• For calcinosis (calcium deposits in the skin), intensification of immunosuppressive therapy should be considered 1

Treatment Duration and Monitoring

• Corticosteroid dose should be weaned as the patient shows clinical improvement 1
• Consider withdrawing treatment if a patient has been off steroids and in remission on MTX (or alternative DMARD) for a minimum of 1 year 1
• Regular monitoring should include assessment of muscle strength using validated measures such as Childhood Myositis Assessment Scale (CMAS) and Manual Muscle Test (MMT) 1
• Monitor for cutaneous disease activity using a cutaneous assessment tool (CAT) including nailfold capillaroscopy 1

Important Considerations and Pitfalls

• Ensure diagnosis is correct before escalating therapy in non-responsive cases; consider repeating muscle biopsy if diagnosis is uncertain 3
• Low-dose MTX (2.5-30 mg weekly) has been shown to be effective as a corticosteroid-sparing agent for cutaneous manifestations 4
• IVIG (2g/kg/month) has demonstrated efficacy in treatment-resistant dermatomyositis 2
• Avoid tapering corticosteroids too quickly as this may lead to disease flare 5
• Initiate steroid-sparing agents early to minimize corticosteroid-related complications 5