Supplementary Material for: Focal Crescentic Pauci-immune Glomerulonephritis in Systemic Lupus Erythematosus (SLE): A Case Report

Introduction: We report a rare case of class III lupus nephritis presenting as crescentic pauci-immune glomerulonephritis—an unusual biopsy finding not captured in the current ISN/RPS classification, highlighting a diagnostic and therapeutic challenge. Case presentation: A 24-year-old woman with systemic lupus erythematosus (SLE) presented with preserved renal function, microscopic hematuria, nephritic-range proteinuria, elevated anti-dsDNA levels, negative ANCA serologies, and a kidney biopsy demonstrating focal crescentic pauci-immune glomerulonephritis with mesangial, subendothelial, and subepithelial electron-dense deposits, consistent with a rare histopathologic variant of class III lupus nephritis. Conclusion: This case underscores the importance of kidney biopsy in atypical lupus presentations, as histopathological findings may not always align with serological or clinical features, and can significantly influence diagnosis, prognosis, and management.