Pauci-immune lupus nephritis: a case report.

A 26-year-old female with systemic lupus erythematosus was admitted because of dyspnea and progressive lower extremity edema. Laboratory testing showed blood urea nitrogen levels of 147 mg/dL, creatinine of 6.7 mg/dL, serum albumin of 1.7 g/dL and the daily protein loss was 12.7 g. Her C3 level was 60.4mg/dL and C4 level was 10.2 mg/dL. The antinuclear antibody titer was 1:320, with a homogeneous pattern, but she was negative for anti-dsDNA. ELISA testing for anti-PR3 antibodies and anti-MPO antibodies were all negative. She was also negative for circulating lupus anticoagulant. Renal biopsy revealed diffuse proliferation of glomerular cells, but immunofluorescent microscopy showed no immune deposits and electron microscopy revealed only scanty electron-dense deposits. She received 1 g/day of methylprednisolone intravenously for 3 days, followed by 60 mg/day of prednisolone. She was discharged with serum creatinine decreased to 4.7 mg/dL, and a great improvement in dyspnea. Diffuse proliferative lupus nephritis that contains little or no subendothelial deposits is rare. The differential diagnosis, possible mechanisms and treatment are discussed.