NXP-2-positive polymyositis associated with scrub typhus.

Area of Science:

• Rheumatology
• Infectious Diseases
• Neurology

Background:

• Polymyositis (PM) is a rare autoimmune disease causing muscle inflammation and weakness.
• Scrub typhus is an infectious disease caused by Orientia tsutsugamushi.
• Distinguishing between infectious myositis and idiopathic inflammatory myopathies can be challenging.

Purpose of the Study:

• To report a unique case of anti-nuclear matrix protein 2 (NXP2) positive polymyositis occurring concurrently with scrub typhus.
• To emphasize the diagnostic complexities and management strategies for overlapping inflammatory and infectious conditions.

Main Methods:

• Case report of a female patient in her 30s presenting with fever and proximal muscle weakness.
• Serological testing for scrub typhus (ELISA IgM), creatine kinase, transaminases, electromyography, nerve conduction studies, and muscle biopsy.
• Detection of myositis-specific anti-NXP-2 antibodies.

Main Results:

• The patient had a history of scrub typhus and presented with symptoms mimicking scrub myositis.
• Diagnostic investigations confirmed anti-NXP-2 positive polymyositis.
• Treatment with corticosteroids, cyclophosphamide, and azathioprine resulted in substantial clinical improvement.

Conclusions:

• Persistent muscle weakness following infection warrants consideration of idiopathic inflammatory myopathy.
• A comprehensive diagnostic approach, including specific antibody testing, is crucial for accurate diagnosis and effective management.
• This case highlights the importance of considering autoimmune myopathies in the context of infectious diseases.