Juvenile Dermatomyositis with Anti-SAE Antibodies in a Moroccan Child Associated with Pseudo-Angioedema: A Case Report Corresponding author: Khalila NAINIA. Faculty of Medicine and Pharmacy. District: Tilila, Bp 7519 Agence Abb Agadir Al Fidia Cp80060, Agadir, Morocco. k.nainia@uiz.ac.ma / Khalila.nainia@gmail.com

Abstract

Abstract Background: Juvenile Dermatomyositis (JDM) is the leading cause of non-infectious inflammatory myopathy in children. it is a heterogeneous group of autoimmune diseases characterized by a variable combination of muscular, dermatological, and visceral involvement. Myositis-specific autoantibodies help define homogeneous subgroups with common clinical characteristics and prognosis. Anti-SAE (small ubiquitin-like modifier 1 (SUMO-1) activating enzyme) antibodies are among the most recently discovered specific autoantibodies. the presence of these antibodies is very rare, making it challenging to define clinical features and prognosis in the juvenile form. We report the first case of African patient with juvenile dermatomyositis and positive anti-SAE antibodies, and the only one reported in the word with pseudo-angioedema. Case Report A 5-year and 3-month-old Moroccan boy presented to the pediatric emergency department with dysphagia that had been evolving for 2 days, preceded two months earlier by facial erythema associated with fatigue, lower limb pain, difficulty walking, and progressive inflammatory polyarthralgia. On admission, the child had a heliotrope rash with predominant pseudo-angioedema on the lips, periungual telangiectasia, and Gottron's papules over the bilateral interphalangeal and metatarsophalangeal joints. He had more pronounced proximal muscle weakness in the lower limbs. He had no fever, arthritis, calcinosis, cutaneous ulcers, or lipodystrophy. Joint examination was normal, as was the pleuropulmonary examination. The electroneuromyography showed myogenic changes in all four limbs. Laboratory findings showed elevated levels of creatine phosphokinase and lactate dehydrogenase and a mild inflammatory syndrome. The electrocardiogram was normal. Only anti-SAE antibodies were positive. He was diagnoses with juvenile dermatomyositis and received methylprednisolone bolus therapy followed by oral prednisone which was gradually tapered in combination with weekly intramuscular methotrexate. Dysphagia disappeared within 48 hours, and after two weeks, there was improvement in the muscular score and significant regression of facial angioedema. However, facial erythema persisted after two months despite local and systemic treatment. Conclusion We report the first African patient with anti-SAE autoantibody-positive JDM. He is the only one described with pseudo-angioedema. He had a typical dermatological, progressive myopathy, dysphagia. He had not fever, weight loss, respiratory signs, arthritis, calcinosis, cutaneous ulcers, lipodystrophy. He responded well to corticosteroid therapy and methotrexate.