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Malignancies Presenting With ANCA Positivity: Two Case Reports and Diagnostic Considerations
1Department of Rheumatology, The First Affiliated Hospital of Dalian Medical University, Dalian, China.
Immunity, Inflammation and Disease
|August 29, 2025
Summary
Malignancies can mimic anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) clinically and serologically. Careful differential diagnosis is crucial for ANCA-positive patients with atypical presentations or poor treatment response.
Area of Science:
- Rheumatology
- Oncology
- Immunology
Background:
- Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are small-vessel inflammatory disorders.
- ANCA positivity, including anti-proteinase 3 (PR3) and anti-myeloperoxidase (MPO) antibodies, can also be present in malignancies, causing diagnostic challenges.
Observation:
- Two cases are presented: a 42-year-old male with lymphoma and an individual with an inflammatory myofibroblastic tumor.
- Both patients initially presented with symptoms and serological findings suggestive of AAV, including elevated PR3-ANCA and MPO-ANCA levels.
Findings:
- Despite immunosuppressive therapy for presumed AAV, one patient experienced persistent fever and deterioration, leading to a lymphoma diagnosis.
- The second patient's tumor was identified through PET-CT and histopathology, highlighting diverse clinical manifestations.
Implications:
- These cases underscore the critical need for comprehensive differential diagnoses in ANCA-positive individuals, especially with atypical clinical courses.
- Understanding the link between tumors and ANCA positivity may involve shared mechanisms like neutrophil extracellular trap formation and autoantigen presentation.
- Further research is essential to clarify these pathophysiological connections and enhance diagnostic accuracy.
