An uncommon cause of rapidly progressive renal failure in a lupus patient: Pauci-immune crescentic glomerulonephritis.

We report a case of systemic lupus erythematosus (SLE) who presented with rapidly progressive renal failure (RPRF) with positive antinuclear antibody (ANA) and anti-double-stranded DNA (dsDNA) antibody and active urinary sediment in the form of microscopic hematuria and proteinuria. Provisional clinical diagnosis of lupus nephritis was made. Renal biopsy showed pauci-immune crescentic glomerulonephritis, the diagnosis of which was supported by positive serum anti-MPO antibody. Renal biopsy in SLE patients can sometimes reveal varied pathological entities such as antinuclear cytoplasmic antibodies (ANCAs) positive vasculitis, as in our case, which modified our treatment protocol. Thus, in a patient with SLE presenting with RPRF with active urinary sediments, ANCA serology, and renal biopsy with immunofluorescence examination should be performed always.