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[Rheumatoid arthritis preceding microscopic polyangitis. Report of two cases]
M Soubrier1, S Le Seaux, J J Dubost
1Service de rhumatologie, hôpital Gabriel-Montpied, CHU, Clermont-Ferrand, France.
Introduction:
Although joint manifestations are common in microscopic polyangiitis (MPA), including arthralgia reported in 15-65% of cases and arthritis in 6-17%, there have been only two published cases of polyarthritis as the first manifestation of the disease. We report on two new cases.
Exegesis:
A 71-year-old woman had symmetric polyarthritis of the hands which initially suggested the existence of seronegative rheumatoid arthritis. A 52-year-old woman had seropositive asymmetric oligoarthritis. The diagnosis was not established until renal insufficiency appeared, prompting a renal biopsy which showed in both cases an extra-capillary glomerulonephritis and an anti-myeloperoxydase (p-ANCA) assay which was postive in both patients. The incidence and specificity of antineutrophil cytoplasmic antibodies (ANCA), including MPA, in rheumatoid arthritis are reviewed.
Conclusion:
Our two observations show that in cases of polyarthritis or oligoarthritis with renal involvement, testing for and typing of ANCA should be performed so as not to misdiagnose vasculitis.
Insights
Microscopic polyangiitis (MPA) can initially present as polyarthritis or oligoarthritis. Early ANCA testing is crucial for accurate diagnosis, especially with kidney involvement, to avoid misdiagnosing vasculitis.
Area of Science:
- Rheumatology
- Nephrology
- Immunology
Background:
- Joint manifestations like arthralgia and arthritis are common in microscopic polyangiitis (MPA).
- Polyarthritis as the initial presenting symptom of MPA is rare, with only two prior cases reported.
- This study presents two new cases of MPA where polyarthritis was the first sign.
Observation:
- A 71-year-old woman presented with symmetric hand polyarthritis, mimicking rheumatoid arthritis.
- A 52-year-old woman had asymmetric oligoarthritis with positive serology.
- Both patients developed renal insufficiency, leading to diagnosis via kidney biopsy showing glomerulonephritis and positive anti-myeloperoxydase (p-ANCA) tests.
Findings:
- The two cases highlight the potential for polyarthritis/oligoarthritis to be the initial presentation of MPA.
- Diagnosis was confirmed by evidence of extra-capillary glomerulonephritis and positive anti-neutrophil cytoplasmic antibodies (ANCA), specifically p-ANCA.
- The review covers the incidence and specificity of ANCA in rheumatoid arthritis and MPA.
Implications:
- Testing for and typing ANCA is essential in patients with polyarthritis or oligoarthritis and renal involvement.
- This diagnostic approach helps prevent misdiagnosis of vasculitis.
- Early and accurate diagnosis of MPA is critical for appropriate management and patient outcomes.