NXP-2-positive polymyositis associated with scrub typhus

Polymyositis (PM), a rare autoimmune inflammatory myopathy, typically presents with symmetric proximal muscle weakness and elevated muscle enzymes. A muscle biopsy is confirmatory for the diagnosis. We report a case of a woman in her 30s with scrub typhus and anti-nuclear matrix protein 2 (NXP2) positive PM. The patient presented with fever, proximal muscle weakness, dysphagia and serologically confirmed scrub typhus a month prior. Laboratory investigations revealed a positive ELISA IgM for scrub typhus, elevated creatine kinase and elevated transaminases, leading to a provisional diagnosis of scrub myositis. However, further investigations, including electromyography, nerve conduction studies, muscle biopsy and the detection of myositis-specific anti-NXP-2 antibodies suggested PM. The patient was successfully treated with corticosteroids, cyclophosphamide and azathioprine, resulting in significant improvement of symptoms. This case highlights the importance of considering idiopathic inflammatory myopathy in patients with persistent muscle weakness and pain and underscores the need for a comprehensive diagnostic approach to ensure prompt and effective treatment.