Abstract
Some cases of patients with IgA nephropathy diagnosed via kidney biopsy and antineutrophil cytoplasmic antibody (ANCA) positivity have been reported. This article describes a case series comprising patients with IgA nephropathy and ANCA positivity seen at a medical center in the city of São Paulo, Brazil, from 1996 to 2016. A total of 111 patients underwent diagnostic kidney biopsies for IgA nephropathy. Five were ANCA-positive at the time of diagnosis; their mean age was 45 ± 15.3 years and they were predominantly females with a mean proteinuria of 2.2 ± 0.9 g/day and a median serum creatinine level of 2.5 (2.0 - 8,6) mg/dL; all had hematuria. Four of the five were cANCA-positive (80%); all had normal serum C3 and C4 levels; and 80% were positive for ANA. One case presented an association with infection, but no associations were found with medication. One patient had granuloma and another had a collapsing lesion. This article describes the cases of five ANCA-positive patients (with predominantly cANCA positivity) submitted to diagnostic kidney biopsies for IgA nephropathy; one patient had a collapsing lesion, but progressed well.
Highlights
immunoglobulin A (IgA) nephropathy (IgAN) is the most common type of glomerulopathy
The presence of IgA deposits in the kidney biopsies of patients with staphylococcal infection has a well defined pathogenesis, while antineutrophil cytoplasmic antibody (ANCA) has been related to significant exposure to neutrophil antigens caused by the massive destruction of neutrophils during infection[6]
The authors usually do not call this condition, when associated with infection, IgA nephropathy, but a post-infection presentation with predominant IgA staining that resolves as the infection is treated[6]
Summary
IgA nephropathy (IgAN) is the most common type of glomerulopathy. Its pathogenesis has been linked to the formation of anomalous immunoglobulin A (IgA). The reported frequency of occurrence of the association between IgAN and antineutrophil cytoplasmic antibody (ANCA) positivity is 1.2%; this combination has not been linked to poorer outcomes[1]. IgA nephropathy with ANCA positivity pathogenic, and that the actual disease is ANCAassociated vasculitis (AAV). This hypothesis was developed based on postmortem studies in which IgA deposits were found in the kidneys of individuals without a history of kidney disease. Another idea is that ANCA is not pathogenic, since in some kidney biopsies no crescents are found, a necessary condition to establish a diagnosis of AAV. Some have pondered about the existence of an association between the two diseases[2]
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