ANCA-Negative Pauci-Immune Necrotizing Glomerulonephritis in the Setting of Multisystem Inflammatory Syndrome in Children.

Multisystem inflammatory syndrome in children (MIS-C) is a rare hyperinflammatory disorder that occurs in previously healthy pediatric patients after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure or mild infection. MIS-C typically has mild kidney symptoms that resolve quickly. The kidney biopsy experience in pediatric coronavirus disease 2019 (COVID-19) and MIS-C is limited in the literature. Here, we describe a 17-year-old SARS-CoV-2 positive boy with features of MIS-C who presented with abdominal pain and gross hematuria. He developed acute kidney injury requiring dialysis. Kidney biopsy and serologic work-up documented antineutrophil cytoplasmic antibody (ANCA)-negative pauci-immune necrotizing glomerulonephritis (AN-PING). Treatment with steroids and intravenous immunoglobulin resulted in simultaneous resolution of the systemic inflammatory markers and kidney symptoms. Aggressive immune suppression and cytotoxic agents were avoided. The glomerulonephritis remained in remission at 3-year follow-up. Although most cases of AN-PING are thought to represent kidney involvement by a primary vasculitis, a subset can occur in association with other conditions. We propose that AN-PING could be a rare kidney manifestation of MIS-C.