Juvenile-Onset Clinically Amyopathic Dermatomyositis

Abstract

Juvenile-onset amyopathic dermatomyositis is an uncommon variant of juvenile-onset dermatomyositis (JDM), characterized by the hallmark cutaneous features of dermatomyositis for at least 6 months without clinical or laboratory evidence of muscle disease. Cutaneous calcinosis, vasculopathy, and interstitial lung disease frequently complicate the course of classic JDM (typical JDM with myositis) but are infrequent in amyopathic JDM. Recent literature suggests that approximately 75% of amyopathic JDM patients will remain free from muscle disease after years of follow-up, while approximately 25% of patients will evolve to having classic JDM. No clinical, laboratory, or ancillary parameters have been found to be predictive for this transition to muscle disease. Treatment of the cutaneous disease of amyopathic JDM centers on photoprotection and topical therapies directed against inflammation. Oral antimalarials are effective for cutaneous disease not adequately controlled with topical care. Systemic corticosteroids, while central to the treatment of classic JDM, are controversial in the treatment of amyopathic JDM. Randomized controlled trials are not available to guide the management of this disease. Proponents for early aggressive systemic corticosteroid therapy for amyopathic JDM advocate that this intervention may decrease the likelihood of progression to classic JDM, and/or prevent disease-specific complications of JDM such as calcinosis. Opponents of early intervention with systemic corticosteroids favor expectant management directed toward controlling skin disease, citing the predictable adverse effects of systemic corticosteroids in the face of uncertain benefit. Other therapeutic options for severe and recalcitrant cutaneous disease, including methotrexate, intravenous immunoglobulin, and rituximab, are reviewed, as are treatment options for calcinosis cutis. In weighing the available evidence, the authors conclude that early aggressive treatment of amyopathic JDM with systemic immunosuppressant agents should be avoided in most cases as the risk of these medications will outweigh the measurable benefit. The reported literature suggests a good prognosis for amyopathic JDM. Ongoing clinical follow-up is recommended in all cases to allow early detection of subtle signs of muscle disease.

Developments in the Classification and Treatment of the Juvenile Idiopathic Inflammatory Myopathies

“…Ultraviolet radiation may lead to local inflammation in the skin and alter the expression of autoantigens 101;102 . Daily application of sunscreens protecting against both UVA and UVB light with an SPF of at least 30 and reapplication after 2 hours in the sun is recommended for patients with JDM, based on expert consensus 103;104 . Use of other photoprotective measures, such as sun avoidance, photoprotective clothing, wide-brimmed hats, and use of laminated glass in car windows may also be helpful 105 .…”

“…Specific use of topical corticosteroids or topical immunomodulators (tacrolimus, pimecrolimus) can be helpful for limited rashes when disease activity is confined to the skin and not amenable to systemic therapy, or for more severe rashes, including scalp involvement 103 . Antihistamines and moisturizers are helpful for treating associated pruritis, given the presence of dermal mast cells in the skin of JDM patients 106 .…”

Childhood Arthritis and Rheumatology Research Alliance consensus clinical treatment plans for juvenile dermatomyositis with skin predominant disease

“…Proposed therapy of skin predominant JDM includes recommendations for topical and systemic therapies, without trial data or case experiences to support these approaches [12]. …”

Update on the management of chronic eczema: new approaches and emerging treatment options

“…Though often highly effective in eliminating the skin inflammation underlying the dermatitis of AD, systemic corticosteroids are not recommended for chronic therapy for AD owing to a high likelihood of significant adverse effects 88. Well-known complications of systemic corticosteroids include suppression of the HPA axis, hyperglycemia, osteoporosis, avascular necrosis of the hip, hypertension, ocular changes (posterior subcapsular cataracts, glaucoma), altered immune function, and altered body habitus.…”

“…Cyclosporine’s cellular mechanism of action involves binding cyclophilin; this complex then inhibits the phosphatase activity of calcineurin, thereby blocking the activation of transcription factor NF-AT (nuclear factor of activated T cells) 88. In a multicenter, double-blind, placebo-controlled crossover study involving 33 patients with severe chronic atopic dermatitis, therapy with cyclosporine for 8 weeks was associated with highly significant improvement of quality of life parameters by multiple clinical indices 92…”