IgA nephropathy with serum ANCA positivity: case series and literature review

The co-occurrence of IgA nephropathy (IgAN) and positive anti-neutrophil cytoplasmic autoantibodies (ANCA) serology is uncommon. In the present case series and literature review, we aimed to clarify the impact of ANCA on pathogenesis, clinical and histopathology presentation, and outcome in IgAN patients. We report four patients with an overlap lesion of IgAN–ANCA positive. Also, we performed a narrative review of all biopsy-proven published case series. Only 1.2% patients had ANCA in our 330-biopsy-proven IgAN cohort. We compared our data with previous reports—6 case series and 3 small retrospective studies—a total of 103 patients. All patients but one had eGFR below 15 mL/min at diagnosis. Besides rapidly decreasing eGFR, all presented with proteinuria around 1.5 g/day and dysmorphic microhematuria, suggesting glomerular inflammation. Systemic symptoms suggestive for ANCA vasculitis were seen in half of our patients, but only one patient had hemorrhagic alveolitis. Patients from our cohort responded to the intensive immunosuppressive regimens used in ANCA-positive vasculitis with renal involvement. However, in the follow-up, one patient had a relapse followed by septic shock related to immunosuppression and one patient started hemodialysis. In the review, we found that IgAN–ANCA -positive patients are characterized by vasculitis-like lesions and clinically by a rapidly progressive decline in kidney function, which was reversed by an aggressive induction immunosuppressive protocol used in ANCA vasculitis. Checking ANCA serology seems useful in patients with rapidly progressive IgAN for therapeutic and prognostic reasons.