Crescentic glomerulonephritis due to IgA nephropathy or propylthiouracil-induced Mpo-Anca positive vasculitis?

Clinicopathological Features and Outcomes of IgA Nephropathy with Serum Antineutrophil Cytoplasmic Autoantibody Positivity

INTRODUCTION

IgA nephropathy (IgAN) with serum antineutrophil cytoplasmic autoantibody (ANCA) positivity is uncommon. This study analyzed the clinicopathologic features and prognosis of IgAN patients with serum ANCA positivity.

METHODS

2,864 IgAN patients were tested for ANCA by the indirect immunofluorescence assay and chemiluminescence immunoassay. Patients with serum ANCA positivity (n = 85) were identified, and their clinical, pathological, and prognostic characteristics were analyzed. They were compared with ANCA-negative IgAN patients (n = 170) and ANCA-associated systemic vasculitis (AAV) with renal involvement patients (n = 85) selected randomly.

RESULTS

2.97% (85/2,864) of IgAN were ANCA positive, and 4 patients were diagnosed as having crescentic IgAN with ANCA positivity. The clinicopathological characteristics of ANCA-positive IgAN patients were comparable to ANCA-negative IgAN patients, but they had higher antinuclear antibody (ANA)-positive rates, lower levels of renal interstitial inflammation, and fewer immune depositions than ANCA-negative IgAN patients. Compared with AAV patients, ANCA-positive IgAN patients were younger and had fewer extrarenal manifestations, milder renal damage, and more immune complex depositions. The renal outcomes were similar between IgAN patients with and without ANCA positivity. Multivariate Cox analysis revealed that in IgAN patients with ANCA positivity, male, ANA positivity, higher serum creatinine and proteinuria, and more severe renal tubular atrophy/interstitial fibrosis were risk factors for adverse renal outcomes.

CONCLUSION

The clinical, pathological features and prognosis of ANCA-positive IgAN patients were similar to those of ANCA-negative IgAN patients except for higher ANA-positive rate, milder renal inflammation, and fewer immune depositions. ANA positivity was an independent risk factor for adverse renal outcomes in ANCA-positive IgAN patients.

Clinical features of IgA nephropathy with serum ANCA positivity: a retrospective case-control study

Background

The coexistence of IgA nephropathy (IgAN) and antineutrophil cytoplasmic autoantibodies (ANCAs) is relatively rare. Only a few studies have reported the features of these patients.

Methods

We studied the clinical and histological features of 20 ANCA-positive IgAN patients. They were compared with ANCA-negative IgAN patients (n = 40) and ANCA-associated systemic vasculitis (AASV) patients (n = 40) with a randomly selected and matched proportion of crescentic glomeruli. Furthermore, 9 ANCA-positive crescentic IgAN patients out of the 20 cases were compared with two control groups with crescentic nephritis.

Results

ANCA-positive IgAN patients showed older age, lower haemoglobin and higher inflammatory indicator levels at baseline, and a higher percentage of general symptoms and pulmonary involvement, compared with ANCA-negative IgAN patients, and were comparable to AASV patients. Histologically, there was a significantly higher percentage of fibrinoid necrosis in glomeruli in ANCA-positive IgAN patients and in AASV patients compared with ANCA-negative IgAN patients (35, 25 and 0%, respectively, P = 0.003). After immunosuppressive therapy, ANCA-positive crescentic IgAN patients were more likely to withdraw from dialysis (75 versus 9.1%, P = 0.03) and not to reach end-stage renal disease within 6 months (11.1 versus 66.7%, P = 0.01) compared with ANCA-negative crescentic IgAN patients.

Conclusions

IgAN patients with ANCA positivity showed more severe clinical and histological features when compared with ANCA-negative IgAN patients and were comparable to AASV patients. However, renal prognosis was relatively better in ANCA-positive crescentic IgAN patients after aggressive immunosuppressive therapy in the short term, compared with ANCA-negative patients.