Clinically Amyopathic Juvenile Dermatomyositis

Abstract

An otherwise healthy 6-year-old girl presented with 4 years of a rash on her hands, feet, elbows, and knees. Previously, she had used treatment with wet wraps and topical steroids without improvement. Her review of systems was notable for rare cough and dyspnea, but negative for muscle weakness. Physical examination revealed ragged cuticles; flat-topped pink papules overlying the bilateral metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints that were consistent with Gottron papules; and a spontaneous skin ulceration on her right knee (Figure). Her muscle strength was normal. Biopsy results of a metacarpophalangeal lesion revealed a lichenoid tissue reaction with basal vacuolation, which was consistent with dermatomyositis. Laboratory study results were notable for an antinuclear antibody titer of 1:320. Aldolase, creatine kinase, and myositis antibody panel results (Quest Diagnostics) were normal. Given the clinicopathologic features, a diagnosis of clinically amyopathic juvenile dermatomyositis (JDM) (CAJDM) was made. Treatment with hydroxychloroquine, prednisone, and clobetasol was administered while care was coordinated with pediatric pulmonology, rheumatology, and physical therapy departments. Ultimately, she was transitioned to receive treatment with methotrexate and intravenous immunoglobulin. At 1-year followup, myositis and interstitial lung disease remained absent and skin findings had improved.Clinically amyopathic dermatomyositis (CADM) is a rare variant of dermatomyositis that may present with some or all of the classic cutaneous findings of dermatomyositis. Heliotrope rash on the upper eyelids is the most common finding. Gottron papules involving the extensor surfaces are pathognomonic. Other findings include periungual telangiectasias, scalp involvement, nonscarring alopecia, and poikiloderma. As suggested by the name, CADM lacks muscular involvement; however, interstitial lung disease, myocarditis, scleroderma, and cancer remain associated with this variant.African American individuals exhibit greater risk of developing dermatomyositis, and African American children with JDM are more likely to develop calcinosis and vasculitis. 1 In contrast, pediatric patients without myopathy have lower rates of vasculopathy, interstitial lung disease, and calcinosis. The average age of diagnosis of CAJDM is 11 years. While some patients may develop classic dermatomyositis, most do not develop myopathy.