Systemic Lupus Erythematosus and ANCA-Associated Vasculitis Overlap Syndrome: A Case Report.

Concomitant lupus nephritis and antineutrophil cytoplasmic antibody-positive crescentic glomerulonephritis is rare, and there is little guidance on the management and outcomes of these patients. A Hispanic woman in her early 40s with no contributory medical history presented with 3 weeks of cough, shortness of breath, fever, and malaise. Laboratory test results were notable for serum creatinine level of 17.4 mg/dL (previously normal), urinalysis with a high hemoglobin level, >182 red blood cell count, and urinary protein-creatinine ratio of 5.72 g/g. Serologies showed elevated dsDNA, ribonucleoprotein antibody, Smith antibody, myeloperoxidase antibody, positive antinuclear antibody, and low complement levels. She was urgently started on hemodialysis and solumedrol 1 g for 3 days. On day 2, she had a kidney biopsy, which showed necrotizing crescentic glomerulonephritis and immunofluorescence with "full house" pattern, immune complex deposits, and strong antinuclear antibody staining of nuclei. She developed diffuse alveolar hemorrhage and was initiated on plasmapheresis and cyclophosphamide. She improved and was discharged without needing further dialysis. Clinicians should consider systemic lupus erythematosus and antineutrophil cytoplasmic antibody disease overlap syndrome when a young, female patient presents with new kidney failure and alveolar hemorrhage. Early biopsy and aggressive treatment are essential in preserving kidney function, and plasmapheresis should be considered in severe cases. This is a severe case with a positive outcome.