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Detection of Anti-MDA5 Autoantibodies Using HeLa Cells and Immunocytochemistry with Light Microscopy
Published on: October 31, 2025
COVID-19-Associated MDA5-Mediated Necrotizing Myositis
Sarah Steadman1, Amit Sikder2, Harsh R Desai3
1Edward Via College of Osteopathic Medicine-Carolinas Campus, Spartanburg, SC, USA.
Abstract:
BACKGROUND Rhabdomyolysis and autoimmune myopathies often present with similar clinical features, including myalgias, muscle weakness, and elevated serum creatine kinase (CK) levels. This overlap can make early diagnosis challenging and delay appropriate management. The recent rise in SARS-CoV-2 infections has led to an increasing number of reports of autoimmune myositis associated with the virus. CASE REPORT Here, we present a unique case of a young African American male who developed myalgias and bilateral upper and lower extremity weakness without any skin changes following a recent SARS-CoV-2 infection. His CK level exceeded 300 000 U/L; however, he had normal inflammatory markers and a basic autoimmune panel, and a chest computed tomography scan did not demonstrate interstitial lung disease. Initial treatment with intravenous fluids for presumed viral-induced rhabdomyolysis showed minimal clinical improvement. Surprisingly, empiric steroid therapy led to a rapid recovery in both CK levels and symptoms. A subsequent muscle biopsy revealed necrotizing myositis, and an autoimmune myositis panel showed elevated melanoma differentiation-associated gene 5 (MDA5) antibodies. CONCLUSIONS To the best of our knowledge, this is the first reported case of MDA5-associated necrotizing myositis following SARS-CoV-2 infection. Most patients with MDA5-related disease develop skin changes and underlying interstitial lung disease; however, our patient lacked these findings. At an 8-month outpatient follow-up, the patient had residual proximal muscle weakness and remained on immunosuppressive therapy. Further research is needed to better understand the pathophysiology of COVID-19-mediated autoimmune myopathies and to develop targeted therapies for these patients.
Insights
This case report details a rare instance of autoimmune myositis linked to SARS-CoV-2 infection. Early diagnosis of COVID-19-related myopathies is crucial for effective treatment and improved patient outcomes.
Area of Science:
- Neurology
- Immunology
- Infectious Diseases
Background:
- Rhabdomyolysis and autoimmune myopathies share symptoms like muscle pain and weakness, complicating diagnosis.
- The SARS-CoV-2 pandemic has seen a rise in reported autoimmune myositis cases.
- Distinguishing viral-induced muscle damage from autoimmune conditions is clinically challenging.
Purpose of the Study:
- To report the first case of melanoma differentiation-associated gene 5 (MDA5)-associated necrotizing myositis following SARS-CoV-2 infection.
- To highlight a unique presentation of COVID-19-related myopathy without typical skin or lung involvement.
- To emphasize the diagnostic challenges and treatment response in post-viral autoimmune myopathies.
Main Methods:
- Clinical case presentation of a young African American male with post-SARS-CoV-2 myopathy.
- Diagnostic workup including serum creatine kinase (CK) levels, inflammatory markers, autoimmune panel, and chest CT.
- Treatment assessment with intravenous fluids and empiric steroid therapy.
- Confirmation via muscle biopsy and specific antibody testing (MDA5).
Main Results:
- Patient presented with severe myalgias and weakness post-COVID-19, with markedly elevated CK levels (>300,000 U/L).
- Initial treatment for rhabdomyolysis yielded poor results, but empiric steroids led to rapid symptom and CK level improvement.
- Muscle biopsy confirmed necrotizing myositis, and elevated MDA5 antibodies were detected.
- The patient lacked typical MDA5-related skin and interstitial lung disease manifestations.
Conclusions:
- This is the first reported case of MDA5-associated necrotizing myositis triggered by SARS-CoV-2 infection.
- The absence of characteristic skin and lung findings in this patient broadens the clinical spectrum of MDA5 myositis.
- Further research is essential to understand COVID-19's role in autoimmune myopathies and develop targeted treatments.
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