Orbital myositis: an uncommon ophthalmic presentation in scleroderma-polymyositis overlap syndrome

Scleroderma-polymyositis overlap syndrome (SSc-PM) is an uncommon autoimmune condition characterised by clinical and serological features of both systemic sclerosis and inflammatory myopathy. Ocular manifestations of this syndrome are rare and insufficiently described in the literature. We report a case of SSc-PM presenting with orbital myositis as the primary manifestation, accompanied by proximal myopathy. A middle-aged woman presented with a 3-month history of progressive finger skin tightening, painless diplopia and restricted eye movements. Ophthalmological evaluation and imaging confirmed bilateral lateral rectus myositis. Laboratory investigations revealed elevated creatine kinase, positive antinuclear antibodies and anti-Ku antibody positivity. Following the rheumatology consultation, she was treated with intravenous methylprednisolone, transitioned to tapering oral prednisolone and initiated on mycophenolate mofetil. Her diplopia resolved completely and muscle enzyme levels normalised. Over 6 months of follow-up, there was no progression of cutaneous or pulmonary disease. This case highlights orbital myositis as a rare but treatable manifestation of SSc-PM, underscoring the importance of early recognition and prompt immunosuppression in overlap syndromes.