Juvenile dermatomyositis forty years on: Case report

Juvenile Dermatomyositis Without Skin Lesions in an Antinuclear Matrix Protein 2 Antibody Seropositive Pediatric Case

ABSTRACT

We report a 5-year-old boy who presented with progressive weakness in 4 limbs and gait disorders over 7 months. No skin rash was observed on admission. A symmetrical proximodistal weakness was found. The creatine kinase level was normal with a slightly elevated lactate dehydrogenase level. Biopsy specimens showed infiltration of mononuclear cells, few necrotic fibers, and perifascicular atrophy. Screening for myositis-specific antibodies was positive for the antinuclear matrix protein 2 antibody, which is mainly associated with dermatomyositis. Symptoms improved on receiving corticosteroids. Our findings suggest that in cases where inflammatory muscle disease is suspected, antinuclear matrix protein 2 antibody analyses should be considered for precise diagnosis, even with the absence of dermatological symptoms. The case suggests consideration of juvenile dermatomyositis in children with no associated skin manifestations or elevated creatine kinase levels and highlights the importance of screening for myositis-specific antibodies in helping with the diagnosis, given the possible heterogeneity of its clinical presentations.

Subcutaneous tissue involvement in idiopathic inflammatory myopathies: Systematic literature review including three new cases and hypothetical mechanisms

INTRODUCTION

Involvement of subcutaneous tissue in idiopathic inflammatory myopathies (IIM) is poorly known.

METHODS

We conducted a systematic review of the literature regarding panniculitis and lipodystrophy/lipoatrophy in juvenile and adult IIM via PubMed/Medline, Embase and Scopus databases. Three local observations are included in this review. Epidemiological, clinical, paraclinical and therapeutic data were collected.

RESULTS

Panniculitis appears to be more common in adults than in juveniles. It was mainly localised in the upper and lower limbs. Panniculitis improved in most cases with steroids and panniculitis and myositis had a similar course in 83.3% and 72.2% of cases in juveniles and adults, respectively. Lipodystrophy appeared to be more frequent in juveniles and was only observed in dermatomyositis in both juveniles and adults. Lipodystrophy was mainly partial in juveniles and adults. The median time from myositis to the diagnosis of lipodystrophy was 6 years [0-35] and 2.5 years [0-10] in juveniles and adults, respectively. Lipodystrophy was associated with anti-TIF1 gamma auto-antibody positivity, a polycyclic/chronic course of myositis and the occurrence of calcinosis and might be an indicator of poor disease control.

CONCLUSION

Adipose tissue involvement, particularly lipodystrophy, occurs almost exclusively in dermatomyositis. The insidious onset and lack of awareness of the diagnosis may underestimate its prevalence. Larger studies are needed to identify possible risk factors in these patients, to better potential underlying pathophysiological process, in order to discuss potential therapeutic targets.

Juvenile Dermatomyositis: Advances in Pathogenesis, Assessment, and Management

BACKGROUND

Juvenile dermatomyositis is the most common inflammatory myopathy in the pediatric age group and a major cause of mortality and morbidity in individuals with childhood rheumatic diseases. Mounting evidence suggests that early diagnosis and timely aggressive treatment are associated with better outcomes.

OBJECTIVE

The purpose of this article is to provide readers with an update on the evaluation, diagnosis, and the treatment of juvenile dermatomyositis.

METHODS

A PubMed search was performed in Clinical Queries using the key term "juvenile dermatomyositis" in the search engine. The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews. The search was restricted to English literature. The information retrieved from the above search was used in the compilation of the present article.

RESULTS

Juvenile dermatomyositis is a chronic autoimmune inflammatory condition characterized by systemic capillary vasculopathy that primarily affects the skin and muscles with possible involvement of other organs. In 2017, the European League Against Rheumatism (EULAR) and the American College of Rheumatology (ACR) developed diagnostic criteria for juvenile idiopathic inflammatory myopathies and juvenile dermatomyositis. In the absence of muscle biopsies which are infrequently performed in children, scores (in brackets) are assigned to four variables related to muscle weakness, three variables related to skin manifestations, one variable related to other clinical manifestations, and two variables related to laboratory measurements to discriminate idiopathic inflammatory myopathies from non-idiopathic inflammatory myopathies as follows: objective symmetric weakness, usually progressive, of the proximal upper extremities (0.7); objective symmetric weakness, usually progressive, of the proximal lower extremities (0.8); neck flexors relatively weaker than neck extensors (1.9); leg proximal muscles relatively weaker than distal muscles (0.9); heliotrope rash (3.1); Gottron papules (2.1); Gottron sign (3.3); dysphagia or esophageal dysmotility (0.7); the presence of anti-Jo-1 autoantibody (3.9); and elevated serum levels of muscle enzymes (1.3). In the absence of muscle biopsy, a definite diagnosis of idiopathic inflammatory myopathy can be made if the total score is ≥7.5. Patients whose age at onset of symptoms is less than 18 years and who meet the above criteria for idiopathic inflammatory myopathy and have a heliotrope rash, Gottron papules or Gottron sign are deemed to have juvenile dermatomyositis. The mainstay of therapy at the time of diagnosis is a high-dose corticosteroid (oral or intravenous) in combination with methotrexate.

CONCLUSION

For mild to moderate active muscle disease, early aggressive treatment with high-dose oral prednisone alone or in combination with methotrexate is the cornerstone of management. Pulse intravenous methylprednisolone is often preferred to oral prednisone in more severely affected patients, patients who respond poorly to oral prednisone, and those with gastrointestinal vasculopathy. Other steroid-sparing immunosuppressive agents such as cyclosporine and cyclophosphamide are reserved for patients with contraindications or intolerance to methotrexate and for refractory cases, as the use of these agents is associated with more adverse events. Various biological agents have been used in the treatment of juvenile dermatomyositis. Data on their efficacy are limited, and their use in the treatment of juvenile dermatomyositis is considered investigational.