Pragathi K Kunder, Suneel Mundkur, Karen Janice Moras, Rochelle Anne Pereira, Shreya Mallya.
Department of Pediatrics, Kasturba Medical College, Manipal academy of higher education (MAHE), Manipal, India.
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Abstract
Orbital myositis, a subtype of idiopathic inflammatory myopathy, rarely presents with isolated superior rectus involvement in adolescents, particularly associated with anti-PM/Scl antibodies.1,2 We report a 16-year-old male with a 3-week history of left eye ptosis and ipsilateral headache. MRI revealed thickening of the left superior rectus muscle with proptosis of the left globe, mimicking infectious or neoplastic processes. Diagnostic workup suggested superior rectus myopathy. Autoimmune profiling identified positive myositis-specific anti-PM/Scl antibodies, consistent with PM/Scl myositis overlap syndrome. Prompt initiation of intravenous methylprednisolone (1 g/day for 3-5 days) led to rapid improvement in ptosis, headache, and proptosis, with near-complete resolution on follow-up imaging. This case underscores the diagnostic utility of myositis specific antibodies in steroid-responsive orbital inflammation, particularly in young patients without systemic features. Early recognition prevents misdiagnosis such as thyroid eye disease or infection, averting unnecessary biopsies or antimicrobials. PM/Scl-associated myositis typically features proximal weakness and interstitial lung disease in adults, but isolated orbital involvement in pediatrics is exceptional, highlighting the need for expanded antibody testing in atypical myopathies. This report adds to sparse pediatric literature on anti-PM/Scl orbital myositis, advocating for multidisciplinary care involving pediatric neurology, ophthalmology, and rheumatology.
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