What is the treatment for dermatomyositis?

Treatment of Dermatomyositis

Start high-dose corticosteroids (oral prednisolone 1-2 mg/kg/day, maximum 60-80 mg/day) combined with methotrexate 15-20 mg/m² weekly administered subcutaneously from the outset of diagnosis. 1, 2, 3

Initial Treatment Strategy

First-Line Dual Therapy

• Initiate corticosteroids and methotrexate simultaneously at diagnosis—dual therapy from the outset improves outcomes compared to sequential addition. 1, 2
• For severe presentations with profound weakness or major organ involvement (such as extensive ulcerative skin disease, cardiac involvement, or interstitial lung disease), administer high-dose intravenous methylprednisolone pulse therapy (15-30 mg/kg/dose on 3 consecutive days) before transitioning to oral prednisolone. 4, 1, 2
• Administer methotrexate subcutaneously rather than orally—subcutaneous administration provides superior absorption and bioavailability. 4, 1, 3

Essential Adjunctive Measures (Start Immediately)

• Prescribe rigorous sun protection to prevent photosensitive rash exacerbations. 4, 1, 3
• Provide calcium and vitamin D supplementation to prevent corticosteroid-induced osteoporosis. 4, 1, 2
• Initiate a supervised physiotherapy program to restore and maintain muscle strength during the remission phase. 1, 2, 3

Treatment Algorithm Based on Response

Assessment Timeline and Monitoring

• Evaluate response at 12 weeks using validated muscle strength measures (Manual Muscle Test [MMT8 ≥78], Childhood Myositis Assessment Scale [CMAS ≥48]). 4, 1, 3
• Monitor creatine phosphokinase (CPK ≤150 U/L), transaminases (AST, ALT), LDH, aldolase, ESR, and CRP. 1
• Assess cardiac involvement with troponin levels. 1
• Monitor skin disease activity systematically—persistent cutaneous disease reflects ongoing systemic inflammation requiring treatment intensification, not just topical management. 3

If Clinical Improvement Occurs (After 2-4 Weeks)

• Begin tapering corticosteroids gradually while maintaining methotrexate. 1, 2, 3
• Continue regular assessments of muscle strength, skin disease, and major organ involvement. 4, 3
• Consider stopping methotrexate only after disease remains in remission for a minimum of 1 year off corticosteroids. 4, 3

If No Improvement at 12 Weeks

• First, verify medication adherence and tolerance before escalating therapy—non-adherence is a common cause of apparent treatment failure. 4, 3

Management of Methotrexate Intolerance

• Switch to mycophenolate mofetil or cyclosporine A as alternative disease-modifying antirheumatic drugs (DMARDs). 4, 1, 3
• Continue corticosteroid taper as tolerated while maintaining the alternative DMARD. 4, 3

Management of Refractory Disease (Inadequate Response Despite Adherence)

Second-Line Intensification Options

• Add intravenous immunoglobulin (IVIG)—shows particular efficacy for cutaneous manifestations and muscle disease. 1, 2, 3
• Add or switch to mycophenolate mofetil or cyclosporine A if not already tried. 4, 1, 3
• For severe disease with major organ involvement, consider cyclophosphamide 500-1000 mg/m² IV monthly. 3

Third-Line Biologic Therapies

• Consider rituximab for refractory cases, but counsel patients that clinical response may take up to 26 weeks—patience is required as improvement is delayed. 1, 3
• Anti-TNF therapies may be considered: use infliximab or adalimumab, NOT etanercept—infliximab and adalimumab are preferred over etanercept based on clinical experience. 1, 3

Management of Persistent Cutaneous Disease

• Intensify systemic immunosuppression for ongoing skin disease—persistent cutaneous manifestations indicate inadequate disease control requiring escalation of systemic therapy, not merely topical management. 3
• Topical tacrolimus or topical corticosteroids may provide symptomatic relief for localized redness or itching but do not substitute for systemic treatment. 3
• Antimalarials may be added for cutaneous manifestations. 5

Special Considerations for Juvenile Dermatomyositis

• Use the same initial approach: corticosteroids 2 mg/kg/day (maximum 60 mg/day) with subcutaneous methotrexate 15 mg/m² weekly. 1, 2
• Monitor vigilantly for calcinosis cutis, cutaneous vasculitis, and gastrointestinal vasculopathy—these complications occur more frequently in juvenile disease and require intensification of immunosuppressive therapy. 1, 2, 3
• Early and aggressive therapy may prevent or stabilize organ damage and disease complications like calcinosis, which is associated with significant morbidity due to pain and risk of infection. 4

Critical Pitfalls to Avoid

• Do not use oral methotrexate when subcutaneous administration is feasible—oral absorption is inferior and may lead to apparent treatment failure. 1
• Do not delay adding methotrexate to corticosteroids—monotherapy with corticosteroids alone is suboptimal; dual therapy from diagnosis improves outcomes. 1
• Do not use etanercept if anti-TNF therapy is considered—infliximab or adalimumab are the preferred anti-TNF agents. 1, 3
• Do not dismiss persistent skin disease as a cosmetic issue—cutaneous activity reflects systemic inflammation requiring treatment escalation. 3
• Do not abruptly discontinue therapy—maintain methotrexate or alternative DMARD for at least 1 year after achieving remission off corticosteroids before considering withdrawal. 4, 3

Malignancy Screening

• Perform careful malignancy evaluation at initial assessment and during follow-up, particularly in adult patients—malignancy is present in approximately 12% of adult dermatomyositis cases. 6, 5
• Evaluate for esophageal, pulmonary, and cardiac disease as part of initial and ongoing assessments. 5