Lupus nephritis with an unusual histopathological pattern

Abstract

Introduction: Systemic lupus erythematosus (SLE) is an autoimmune disease that can affect multiple organs. When the kidney is involved it is generally termed lupus nephritis (LN), and is a major contributor to the morbidity and mortality associated with SLE. The classic pattern of lupus nephritis in a renal biopsy is an immune complex mediated glomerulonephritis. The presence of crescents, in diffuse proliferative lupus nephritis, and serologic positivity for antineutrophil cytoplasmatic antibodies (ANCA), more often antimyeloperoxidase than anti-proteinase 3, has been linked with specific clinicopathological features, poor treatment response and a worse kidney survival. Clinical case: We present the case of a 19-year-old male, without relevant past medical history, who presented severe headaches, hypertension and peripheral edema. The blood analysis revealed hemoglobin (Hb) 7.6 g/dL, creatinine (Cr) 2.64 mg/dL, blood urea nitrogen (BUN) 101 mg/dL, and urine analysis, hematuria and nephrotic proteinuria. The autoimmunity panel results were consistent with SLE paired with positivity for ANCA-proteinase 3 antibody. A renal biopsy revealed crescentic glomerulonephritis with fibrinoid necrosis and Bowman capsule rupture. The patient was diagnosed with class IV LN. The initiation treatment consisted of cyclophosphamide (CIPH) and prednisolone (PDN). At the 6-month follow-up, CIPH was stopped and mycophenolate mofetil (MMF) initiated as maintenance therapy, combined with PDN. Although microscopic hematuria and C3 consumption were still present (a new biopsy was pondered but the patient refused any further invasive diagnostic measures), C1q levels decreased from 26.6 to 19.3 U/ml (negative if < 20 U/ml) and anti-dsDNA was also negative with progressive declination of the degree of proteinuria. The creatinine levels returned to normal. Conclusion: The authors emphasize the importance of this class IV LN, influenced by the association with anti-proteinase 3, due to the implications in the histopathological pattern and in therapy selection. In this specific case kidney function, proteinuria and lupus activity had an important decrease without significant complications with the chosen treatment.