E58 The rheumatologic masquerader: a case report on SLE-dermatomyositis-systemic scleroderma overlap syndrome
Authors: Kaniu Mary , Owende Deogracia , Migowa Angela 
Published: August 2023

Abstract

Introduction
Juvenile dermatomyositis is an autoimmune connective tissue disorder characterized by idiopathic inflammatory myopathy primarily affecting the skin and muscles(1, 2). It may occur alone or in overlap syndromes usually with systemic scleroderma, systemic lupus erythematosus (SLE) and mixed connective tissue disease(3, 4). There is need to further describe and characterize cases encountered in different set ups.

Objective
To describe a case of dermatomyositis-scleroderma overlap in an African male adolescent.

Methods
We carried out a retrospective chart review to ascertain clinical features and management strategies.

Results
We present a case of a 17- year old African male patient who presented with a diagnosis of systemic lupus erythematosus made at a peripheral facility in February 2021, and started on azathioprine 50 mg daily, hydroxychloroquine 200 mg daily and prednisolone 5 mg twice daily.
He presented on 30th November 2022 with a 2-year history of bilateral elbow, knee, ankle pain and swelling with an 8-month history of bilateral proximal upper and lower limb muscle weakness.
Review of systems revealed alopecia, occasional fever and hyperpigmentation over his proximal interphalangeal and metacarpophalangeal joints that has since evolved to hypopigmentation.
Positive examination findings included fine sparse hair, heliotrope rash, Gottron's papule, salt and pepper skin rash, hardening of the skin over the arm and thighs with a rodnan score 3/3 over the phalanges, nodular non tender lesions in the abdominal subcutaneous tissue and dactylitis with fixed flexion deformities of both elbows. He had bilateral flexion contractures of both elbows and knees with dactylitic fingers.
Laboratory investigations showed an elevated CRP 94 mg/l, elevated lactate dehydrogenase 458 U/l, elevated creatine kinase 492U/l, positive antinuclear antibodies (1:640 titres) with a nuclear coarse and large speckled pattern, positive double stranded DNA antibodies and weak positive anti SM, anti RNP and PCNA antibodies. Myositis panel was positive for MDA5 and OJ.
Pelvic MRI showed features of proximal inflammatory myositis. The childhood myositis assessment scale revealed a score of 25/52. ECHO and chest radiograph were normal. Pulmonary function test showed a low FEV 1 and FVC in keeping with a restrictive lung picture. Gastroenterology review revealed gastritis with no other stigmata of autoimmune disease.
Management has consisted of monthly therapy with intravenous immunoglobulin. Azathioprine therapy was switched with mycophenolate mofetil 1 gram twelve hourly. He was advised on sunscreen protection. Physiotherapy and occupational therapy has been ongoing. Three months of follow up has led to the resolution of the flexion knee contractures, improved functionality in activities of daily living and a rodnan score of 2/3 over the phalanges.

Conclusion
SLE-juvenile dermatomyositis and systemic scleroderma can occur as an overlap syndrome and a definitive diagnosis remains elusive to many clinicians. A thorough history and comprehensive physical examination remains key to establishing a correct diagnosis. Early patient referral to paediatric rheumatologist for prompt appropriate treatment can avert debilitating morbidity and mortality.

References
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2. Li D, Tansley SL. Juvenile dermatomyositis-clinical phenotypes. Curr Rheumatol Rep 2019;21:74.
3. Colafrancesco S, Priori R, Valesini G. Inflammatory myopathies and overlap syndromes: update on histological and serological profile. Best Pract Res Clin Rheumatol. 2015;29:810–25.
4. Rider LG, Shah M, Mamyrova G et al. The myositis autoantibody phenotypes of the juvenile idiopathic inflammatory myopathies. Medicine (Baltimore) 2013;92:223–43.