ANCA-associated vasculitis and severe proximal muscle weakness

Area of Science:

• Rheumatology
• Neurology
• Immunology

Background:

• ANCA-associated vasculitis encompasses a group of autoimmune diseases characterized by inflammation of blood vessels.
• Granulomatosis with polyangiitis (GPA) is a specific form of ANCA-associated vasculitis with diverse clinical manifestations.
• Musculoskeletal symptoms, such as myositis, can be an initial presentation of GPA.

Observation:

• A patient presented with proximal muscle weakness and pain, initially suggesting primary myositis.
• Normal creatine kinase levels and absence of muscular antibodies excluded primary myositis.
• Brain MRI revealed characteristic deep gray matter lesions, and positive serologies supported a diagnosis of GPA.

Findings:

• The case highlights the association between granulomatosis with polyangiitis and myositis.
• GPA can be misdiagnosed if musculoskeletal symptoms are the primary presenting feature.
• Diagnostic challenges arise when vasculitis mimics other conditions.

Implications:

• Increased awareness of GPA presenting as myositis is essential for timely diagnosis.
• Prompt recognition and aggressive treatment of GPA can prevent multiorgan failure.
• This case underscores the importance of considering systemic autoimmune diseases in patients with unexplained myopathic symptoms.